/*
 * Copyright © 2008-2015 Intel Corporation
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 *
 * Authors:
 *    Eric Anholt <eric@anholt.net>
 *
 */

#include <drm/drmP.h>
#include <drm/drm_vma_manager.h>
#include <drm/i915_drm.h>
#include "i915_drv.h"
#include "i915_vgpu.h"
#include "i915_trace.h"
#include "intel_drv.h"
#include "intel_mocs.h"
#include <linux/shmem_fs.h>
#include <linux/slab.h>
#include <linux/swap.h>
#include <linux/pci.h>
#include <linux/dma-buf.h>

static void i915_gem_object_flush_gtt_write_domain(struct drm_i915_gem_object *obj);
static void i915_gem_object_flush_cpu_write_domain(struct drm_i915_gem_object *obj);
static void
i915_gem_object_retire__write(struct drm_i915_gem_object *obj);
static void
i915_gem_object_retire__read(struct drm_i915_gem_object *obj, int ring);

static bool cpu_cache_is_coherent(struct drm_device *dev,
                                  enum i915_cache_level level)
{
        return HAS_LLC(dev) || level != I915_CACHE_NONE;
}

static bool cpu_write_needs_clflush(struct drm_i915_gem_object *obj)
{
        if (!cpu_cache_is_coherent(obj->base.dev, obj->cache_level))
                return true;

        return obj->pin_display;
}

/* some bookkeeping */
static void i915_gem_info_add_obj(struct drm_i915_private *dev_priv,
                                  size_t size)
{
        spin_lock(&dev_priv->mm.object_stat_lock);
        dev_priv->mm.object_count++;
        dev_priv->mm.object_memory += size;
        spin_unlock(&dev_priv->mm.object_stat_lock);
}

static void i915_gem_info_remove_obj(struct drm_i915_private *dev_priv,
                                     size_t size)
{
        spin_lock(&dev_priv->mm.object_stat_lock);
        dev_priv->mm.object_count--;
        dev_priv->mm.object_memory -= size;
        spin_unlock(&dev_priv->mm.object_stat_lock);
}

static int
i915_gem_wait_for_error(struct i915_gpu_error *error)
{
        int ret;

        if (!i915_reset_in_progress(error))
                return 0;

        /*
         * Only wait 10 seconds for the gpu reset to complete to avoid hanging
         * userspace. If it takes that long something really bad is going on and
         * we should simply try to bail out and fail as gracefully as possible.
         */
        ret = wait_event_interruptible_timeout(error->reset_queue,
                                               !i915_reset_in_progress(error),
                                               10*HZ);
        if (ret == 0) {
                DRM_ERROR("Timed out waiting for the gpu reset to complete\n");
                return -EIO;
        } else if (ret < 0) {
                return ret;
        } else {
                return 0;
        }
}

int i915_mutex_lock_interruptible(struct drm_device *dev)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        int ret;

        ret = i915_gem_wait_for_error(&dev_priv->gpu_error);
        if (ret)
                return ret;

        ret = mutex_lock_interruptible(&dev->struct_mutex);
        if (ret)
                return ret;

        WARN_ON(i915_verify_lists(dev));
        return 0;
}

int
i915_gem_get_aperture_ioctl(struct drm_device *dev, void *data,
                            struct drm_file *file)
{
        struct drm_i915_private *dev_priv = to_i915(dev);
        struct i915_ggtt *ggtt = &dev_priv->ggtt;
        struct drm_i915_gem_get_aperture *args = data;
        struct i915_vma *vma;
        size_t pinned;

        pinned = 0;
        mutex_lock(&dev->struct_mutex);
        list_for_each_entry(vma, &ggtt->base.active_list, vm_link)
                if (vma->pin_count)
                        pinned += vma->node.size;
        list_for_each_entry(vma, &ggtt->base.inactive_list, vm_link)
                if (vma->pin_count)
                        pinned += vma->node.size;
        mutex_unlock(&dev->struct_mutex);

        args->aper_size = ggtt->base.total;
        args->aper_available_size = args->aper_size - pinned;

        return 0;
}

static int
i915_gem_object_get_pages_phys(struct drm_i915_gem_object *obj)
{
        struct address_space *mapping = file_inode(obj->base.filp)->i_mapping;
        char *vaddr = obj->phys_handle->vaddr;
        struct sg_table *st;
        struct scatterlist *sg;
        int i;

        if (WARN_ON(i915_gem_object_needs_bit17_swizzle(obj)))
                return -EINVAL;

        for (i = 0; i < obj->base.size / PAGE_SIZE; i++) {
                struct page *page;
                char *src;

                page = shmem_read_mapping_page(mapping, i);
                if (IS_ERR(page))
                        return PTR_ERR(page);

                src = kmap_atomic(page);
                memcpy(vaddr, src, PAGE_SIZE);
                drm_clflush_virt_range(vaddr, PAGE_SIZE);
                kunmap_atomic(src);

                put_page(page);
                vaddr += PAGE_SIZE;
        }

        i915_gem_chipset_flush(obj->base.dev);

        st = kmalloc(sizeof(*st), GFP_KERNEL);
        if (st == NULL)
                return -ENOMEM;

        if (sg_alloc_table(st, 1, GFP_KERNEL)) {
                kfree(st);
                return -ENOMEM;
        }

        sg = st->sgl;
        sg->offset = 0;
        sg->length = obj->base.size;

        sg_dma_address(sg) = obj->phys_handle->busaddr;
        sg_dma_len(sg) = obj->base.size;

        obj->pages = st;
        return 0;
}

static void
i915_gem_object_put_pages_phys(struct drm_i915_gem_object *obj)
{
        int ret;

        BUG_ON(obj->madv == __I915_MADV_PURGED);

        ret = i915_gem_object_set_to_cpu_domain(obj, true);
        if (WARN_ON(ret)) {
                /* In the event of a disaster, abandon all caches and
                 * hope for the best.
                 */
                obj->base.read_domains = obj->base.write_domain = I915_GEM_DOMAIN_CPU;
        }

        if (obj->madv == I915_MADV_DONTNEED)
                obj->dirty = 0;

        if (obj->dirty) {
                struct address_space *mapping = file_inode(obj->base.filp)->i_mapping;
                char *vaddr = obj->phys_handle->vaddr;
                int i;

                for (i = 0; i < obj->base.size / PAGE_SIZE; i++) {
                        struct page *page;
                        char *dst;

                        page = shmem_read_mapping_page(mapping, i);
                        if (IS_ERR(page))
                                continue;

                        dst = kmap_atomic(page);
                        drm_clflush_virt_range(vaddr, PAGE_SIZE);
                        memcpy(dst, vaddr, PAGE_SIZE);
                        kunmap_atomic(dst);

                        set_page_dirty(page);
                        if (obj->madv == I915_MADV_WILLNEED)
                                mark_page_accessed(page);
                        put_page(page);
                        vaddr += PAGE_SIZE;
                }
                obj->dirty = 0;
        }

        sg_free_table(obj->pages);
        kfree(obj->pages);
}

static void
i915_gem_object_release_phys(struct drm_i915_gem_object *obj)
{
        drm_pci_free(obj->base.dev, obj->phys_handle);
}

static const struct drm_i915_gem_object_ops i915_gem_phys_ops = {
        .get_pages = i915_gem_object_get_pages_phys,
        .put_pages = i915_gem_object_put_pages_phys,
        .release = i915_gem_object_release_phys,
};

static int
drop_pages(struct drm_i915_gem_object *obj)
{
        struct i915_vma *vma, *next;
        int ret;

        drm_gem_object_reference(&obj->base);
        list_for_each_entry_safe(vma, next, &obj->vma_list, obj_link)
                if (i915_vma_unbind(vma))
                        break;

        ret = i915_gem_object_put_pages(obj);
        drm_gem_object_unreference(&obj->base);

        return ret;
}

int
i915_gem_object_attach_phys(struct drm_i915_gem_object *obj,
                            int align)
{
        drm_dma_handle_t *phys;
        int ret;

        if (obj->phys_handle) {
                if ((unsigned long)obj->phys_handle->vaddr & (align -1))
                        return -EBUSY;

                return 0;
        }

        if (obj->madv != I915_MADV_WILLNEED)
                return -EFAULT;

        if (obj->base.filp == NULL)
                return -EINVAL;

        ret = drop_pages(obj);
        if (ret)
                return ret;

        /* create a new object */
        phys = drm_pci_alloc(obj->base.dev, obj->base.size, align);
        if (!phys)
                return -ENOMEM;

        obj->phys_handle = phys;
        obj->ops = &i915_gem_phys_ops;

        return i915_gem_object_get_pages(obj);
}

static int
i915_gem_phys_pwrite(struct drm_i915_gem_object *obj,
                     struct drm_i915_gem_pwrite *args,
                     struct drm_file *file_priv)
{
        struct drm_device *dev = obj->base.dev;
        void *vaddr = obj->phys_handle->vaddr + args->offset;
        char __user *user_data = u64_to_user_ptr(args->data_ptr);
        int ret = 0;

        /* We manually control the domain here and pretend that it
         * remains coherent i.e. in the GTT domain, like shmem_pwrite.
         */
        ret = i915_gem_object_wait_rendering(obj, false);
        if (ret)
                return ret;

        intel_fb_obj_invalidate(obj, ORIGIN_CPU);
        if (__copy_from_user_inatomic_nocache(vaddr, user_data, args->size)) {
                unsigned long unwritten;

                /* The physical object once assigned is fixed for the lifetime
                 * of the obj, so we can safely drop the lock and continue
                 * to access vaddr.
                 */
                mutex_unlock(&dev->struct_mutex);
                unwritten = copy_from_user(vaddr, user_data, args->size);
                mutex_lock(&dev->struct_mutex);
                if (unwritten) {
                        ret = -EFAULT;
                        goto out;
                }
        }

        drm_clflush_virt_range(vaddr, args->size);
        i915_gem_chipset_flush(dev);

out:
        intel_fb_obj_flush(obj, false, ORIGIN_CPU);
        return ret;
}

void *i915_gem_object_alloc(struct drm_device *dev)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        return kmem_cache_zalloc(dev_priv->objects, GFP_KERNEL);
}

void i915_gem_object_free(struct drm_i915_gem_object *obj)
{
        struct drm_i915_private *dev_priv = obj->base.dev->dev_private;
        kmem_cache_free(dev_priv->objects, obj);
}

static int
i915_gem_create(struct drm_file *file,
                struct drm_device *dev,
                uint64_t size,
                uint32_t *handle_p)
{
        struct drm_i915_gem_object *obj;
        int ret;
        u32 handle;

        size = roundup(size, PAGE_SIZE);
        if (size == 0)
                return -EINVAL;

        /* Allocate the new object */
        obj = i915_gem_alloc_object(dev, size);
        if (obj == NULL)
                return -ENOMEM;

        ret = drm_gem_handle_create(file, &obj->base, &handle);
        /* drop reference from allocate - handle holds it now */
        drm_gem_object_unreference_unlocked(&obj->base);
        if (ret)
                return ret;

        *handle_p = handle;
        return 0;
}

int
i915_gem_dumb_create(struct drm_file *file,
                     struct drm_device *dev,
                     struct drm_mode_create_dumb *args)
{
        /* have to work out size/pitch and return them */
        args->pitch = ALIGN(args->width * DIV_ROUND_UP(args->bpp, 8), 64);
        args->size = args->pitch * args->height;
        return i915_gem_create(file, dev,
                               args->size, &args->handle);
}

/**
 * Creates a new mm object and returns a handle to it.
 */
int
i915_gem_create_ioctl(struct drm_device *dev, void *data,
                      struct drm_file *file)
{
        struct drm_i915_gem_create *args = data;

        return i915_gem_create(file, dev,
                               args->size, &args->handle);
}

static inline int
__copy_to_user_swizzled(char __user *cpu_vaddr,
                        const char *gpu_vaddr, int gpu_offset,
                        int length)
{
        int ret, cpu_offset = 0;

        while (length > 0) {
                int cacheline_end = ALIGN(gpu_offset + 1, 64);
                int this_length = min(cacheline_end - gpu_offset, length);
                int swizzled_gpu_offset = gpu_offset ^ 64;

                ret = __copy_to_user(cpu_vaddr + cpu_offset,
                                     gpu_vaddr + swizzled_gpu_offset,
                                     this_length);
                if (ret)
                        return ret + length;

                cpu_offset += this_length;
                gpu_offset += this_length;
                length -= this_length;
        }

        return 0;
}

static inline int
__copy_from_user_swizzled(char *gpu_vaddr, int gpu_offset,
                          const char __user *cpu_vaddr,
                          int length)
{
        int ret, cpu_offset = 0;

        while (length > 0) {
                int cacheline_end = ALIGN(gpu_offset + 1, 64);
                int this_length = min(cacheline_end - gpu_offset, length);
                int swizzled_gpu_offset = gpu_offset ^ 64;

                ret = __copy_from_user(gpu_vaddr + swizzled_gpu_offset,
                                       cpu_vaddr + cpu_offset,
                                       this_length);
                if (ret)
                        return ret + length;

                cpu_offset += this_length;
                gpu_offset += this_length;
                length -= this_length;
        }

        return 0;
}

/*
 * Pins the specified object's pages and synchronizes the object with
 * GPU accesses. Sets needs_clflush to non-zero if the caller should
 * flush the object from the CPU cache.
 */
int i915_gem_obj_prepare_shmem_read(struct drm_i915_gem_object *obj,
                                    int *needs_clflush)
{
        int ret;

        *needs_clflush = 0;

        if (WARN_ON((obj->ops->flags & I915_GEM_OBJECT_HAS_STRUCT_PAGE) == 0))
                return -EINVAL;

        if (!(obj->base.read_domains & I915_GEM_DOMAIN_CPU)) {
                /* If we're not in the cpu read domain, set ourself into the gtt
                 * read domain and manually flush cachelines (if required). This
                 * optimizes for the case when the gpu will dirty the data
                 * anyway again before the next pread happens. */
                *needs_clflush = !cpu_cache_is_coherent(obj->base.dev,
                                                        obj->cache_level);
                ret = i915_gem_object_wait_rendering(obj, true);
                if (ret)
                        return ret;
        }

        ret = i915_gem_object_get_pages(obj);
        if (ret)
                return ret;

        i915_gem_object_pin_pages(obj);

        return ret;
}

/* Per-page copy function for the shmem pread fastpath.
 * Flushes invalid cachelines before reading the target if
 * needs_clflush is set. */
static int
shmem_pread_fast(struct page *page, int shmem_page_offset, int page_length,
                 char __user *user_data,
                 bool page_do_bit17_swizzling, bool needs_clflush)
{
        char *vaddr;
        int ret;

        if (unlikely(page_do_bit17_swizzling))
                return -EINVAL;

        vaddr = kmap_atomic(page);
        if (needs_clflush)
                drm_clflush_virt_range(vaddr + shmem_page_offset,
                                       page_length);
        ret = __copy_to_user_inatomic(user_data,
                                      vaddr + shmem_page_offset,
                                      page_length);
        kunmap_atomic(vaddr);

        return ret ? -EFAULT : 0;
}

static void
shmem_clflush_swizzled_range(char *addr, unsigned long length,
                             bool swizzled)
{
        if (unlikely(swizzled)) {
                unsigned long start = (unsigned long) addr;
                unsigned long end = (unsigned long) addr + length;

                /* For swizzling simply ensure that we always flush both
                 * channels. Lame, but simple and it works. Swizzled
                 * pwrite/pread is far from a hotpath - current userspace
                 * doesn't use it at all. */
                start = round_down(start, 128);
                end = round_up(end, 128);

                drm_clflush_virt_range((void *)start, end - start);
        } else {
                drm_clflush_virt_range(addr, length);
        }

}

/* Only difference to the fast-path function is that this can handle bit17
 * and uses non-atomic copy and kmap functions. */
static int
shmem_pread_slow(struct page *page, int shmem_page_offset, int page_length,
                 char __user *user_data,
                 bool page_do_bit17_swizzling, bool needs_clflush)
{
        char *vaddr;
        int ret;

        vaddr = kmap(page);
        if (needs_clflush)
                shmem_clflush_swizzled_range(vaddr + shmem_page_offset,
                                             page_length,
                                             page_do_bit17_swizzling);

        if (page_do_bit17_swizzling)
                ret = __copy_to_user_swizzled(user_data,
                                              vaddr, shmem_page_offset,
                                              page_length);
        else
                ret = __copy_to_user(user_data,
                                     vaddr + shmem_page_offset,
                                     page_length);
        kunmap(page);

        return ret ? - EFAULT : 0;
}

static int
i915_gem_shmem_pread(struct drm_device *dev,
                     struct drm_i915_gem_object *obj,
                     struct drm_i915_gem_pread *args,
                     struct drm_file *file)
{
        char __user *user_data;
        ssize_t remain;
        loff_t offset;
        int shmem_page_offset, page_length, ret = 0;
        int obj_do_bit17_swizzling, page_do_bit17_swizzling;
        int prefaulted = 0;
        int needs_clflush = 0;
        struct sg_page_iter sg_iter;

        user_data = u64_to_user_ptr(args->data_ptr);
        remain = args->size;

        obj_do_bit17_swizzling = i915_gem_object_needs_bit17_swizzle(obj);

        ret = i915_gem_obj_prepare_shmem_read(obj, &needs_clflush);
        if (ret)
                return ret;

        offset = args->offset;

        for_each_sg_page(obj->pages->sgl, &sg_iter, obj->pages->nents,
                         offset >> PAGE_SHIFT) {
                struct page *page = sg_page_iter_page(&sg_iter);

                if (remain <= 0)
                        break;

                /* Operation in this page
                 *
                 * shmem_page_offset = offset within page in shmem file
                 * page_length = bytes to copy for this page
                 */
                shmem_page_offset = offset_in_page(offset);
                page_length = remain;
                if ((shmem_page_offset + page_length) > PAGE_SIZE)
                        page_length = PAGE_SIZE - shmem_page_offset;

                page_do_bit17_swizzling = obj_do_bit17_swizzling &&
                        (page_to_phys(page) & (1 << 17)) != 0;

                ret = shmem_pread_fast(page, shmem_page_offset, page_length,
                                       user_data, page_do_bit17_swizzling,
                                       needs_clflush);
                if (ret == 0)
                        goto next_page;

                mutex_unlock(&dev->struct_mutex);

                if (likely(!i915.prefault_disable) && !prefaulted) {
                        ret = fault_in_multipages_writeable(user_data, remain);
                        /* Userspace is tricking us, but we've already clobbered
                         * its pages with the prefault and promised to write the
                         * data up to the first fault. Hence ignore any errors
                         * and just continue. */
                        (void)ret;
                        prefaulted = 1;
                }

                ret = shmem_pread_slow(page, shmem_page_offset, page_length,
                                       user_data, page_do_bit17_swizzling,
                                       needs_clflush);

                mutex_lock(&dev->struct_mutex);

                if (ret)
                        goto out;

next_page:
                remain -= page_length;
                user_data += page_length;
                offset += page_length;
        }

out:
        i915_gem_object_unpin_pages(obj);

        return ret;
}

/**
 * Reads data from the object referenced by handle.
 *
 * On error, the contents of *data are undefined.
 */
int
i915_gem_pread_ioctl(struct drm_device *dev, void *data,
                     struct drm_file *file)
{
        struct drm_i915_gem_pread *args = data;
        struct drm_i915_gem_object *obj;
        int ret = 0;

        if (args->size == 0)
                return 0;

        if (!access_ok(VERIFY_WRITE,
                       u64_to_user_ptr(args->data_ptr),
                       args->size))
                return -EFAULT;

        ret = i915_mutex_lock_interruptible(dev);
        if (ret)
                return ret;

        obj = to_intel_bo(drm_gem_object_lookup(file, args->handle));
        if (&obj->base == NULL) {
                ret = -ENOENT;
                goto unlock;
        }

        /* Bounds check source.  */
        if (args->offset > obj->base.size ||
            args->size > obj->base.size - args->offset) {
                ret = -EINVAL;
                goto out;
        }

        /* prime objects have no backing filp to GEM pread/pwrite
         * pages from.
         */
        if (!obj->base.filp) {
                ret = -EINVAL;
                goto out;
        }

        trace_i915_gem_object_pread(obj, args->offset, args->size);

        ret = i915_gem_shmem_pread(dev, obj, args, file);

out:
        drm_gem_object_unreference(&obj->base);
unlock:
        mutex_unlock(&dev->struct_mutex);
        return ret;
}

/* This is the fast write path which cannot handle
 * page faults in the source data
 */

static inline int
fast_user_write(struct io_mapping *mapping,
                loff_t page_base, int page_offset,
                char __user *user_data,
                int length)
{
        void __iomem *vaddr_atomic;
        void *vaddr;
        unsigned long unwritten;

        vaddr_atomic = io_mapping_map_atomic_wc(mapping, page_base);
        /* We can use the cpu mem copy function because this is X86. */
        vaddr = (void __force*)vaddr_atomic + page_offset;
        unwritten = __copy_from_user_inatomic_nocache(vaddr,
                                                      user_data, length);
        io_mapping_unmap_atomic(vaddr_atomic);
        return unwritten;
}

/**
 * This is the fast pwrite path, where we copy the data directly from the
 * user into the GTT, uncached.
 */
static int
i915_gem_gtt_pwrite_fast(struct drm_device *dev,
                         struct drm_i915_gem_object *obj,
                         struct drm_i915_gem_pwrite *args,
                         struct drm_file *file)
{
        struct drm_i915_private *dev_priv = to_i915(dev);
        struct i915_ggtt *ggtt = &dev_priv->ggtt;
        ssize_t remain;
        loff_t offset, page_base;
        char __user *user_data;
        int page_offset, page_length, ret;

        ret = i915_gem_obj_ggtt_pin(obj, 0, PIN_MAPPABLE | PIN_NONBLOCK);
        if (ret)
                goto out;

        ret = i915_gem_object_set_to_gtt_domain(obj, true);
        if (ret)
                goto out_unpin;

        ret = i915_gem_object_put_fence(obj);
        if (ret)
                goto out_unpin;

        user_data = u64_to_user_ptr(args->data_ptr);
        remain = args->size;

        offset = i915_gem_obj_ggtt_offset(obj) + args->offset;

        intel_fb_obj_invalidate(obj, ORIGIN_GTT);

        while (remain > 0) {
                /* Operation in this page
                 *
                 * page_base = page offset within aperture
                 * page_offset = offset within page
                 * page_length = bytes to copy for this page
                 */
                page_base = offset & PAGE_MASK;
                page_offset = offset_in_page(offset);
                page_length = remain;
                if ((page_offset + remain) > PAGE_SIZE)
                        page_length = PAGE_SIZE - page_offset;

                /* If we get a fault while copying data, then (presumably) our
                 * source page isn't available.  Return the error and we'll
                 * retry in the slow path.
                 */
                if (fast_user_write(ggtt->mappable, page_base,
                                    page_offset, user_data, page_length)) {
                        ret = -EFAULT;
                        goto out_flush;
                }

                remain -= page_length;
                user_data += page_length;
                offset += page_length;
        }

out_flush:
        intel_fb_obj_flush(obj, false, ORIGIN_GTT);
out_unpin:
        i915_gem_object_ggtt_unpin(obj);
out:
        return ret;
}

/* Per-page copy function for the shmem pwrite fastpath.
 * Flushes invalid cachelines before writing to the target if
 * needs_clflush_before is set and flushes out any written cachelines after
 * writing if needs_clflush is set. */
static int
shmem_pwrite_fast(struct page *page, int shmem_page_offset, int page_length,
                  char __user *user_data,
                  bool page_do_bit17_swizzling,
                  bool needs_clflush_before,
                  bool needs_clflush_after)
{
        char *vaddr;
        int ret;

        if (unlikely(page_do_bit17_swizzling))
                return -EINVAL;

        vaddr = kmap_atomic(page);
        if (needs_clflush_before)
                drm_clflush_virt_range(vaddr + shmem_page_offset,
                                       page_length);
        ret = __copy_from_user_inatomic(vaddr + shmem_page_offset,
                                        user_data, page_length);
        if (needs_clflush_after)
                drm_clflush_virt_range(vaddr + shmem_page_offset,
                                       page_length);
        kunmap_atomic(vaddr);

        return ret ? -EFAULT : 0;
}

/* Only difference to the fast-path function is that this can handle bit17
 * and uses non-atomic copy and kmap functions. */
static int
shmem_pwrite_slow(struct page *page, int shmem_page_offset, int page_length,
                  char __user *user_data,
                  bool page_do_bit17_swizzling,
                  bool needs_clflush_before,
                  bool needs_clflush_after)
{
        char *vaddr;
        int ret;

        vaddr = kmap(page);
        if (unlikely(needs_clflush_before || page_do_bit17_swizzling))
                shmem_clflush_swizzled_range(vaddr + shmem_page_offset,
                                             page_length,
                                             page_do_bit17_swizzling);
        if (page_do_bit17_swizzling)
                ret = __copy_from_user_swizzled(vaddr, shmem_page_offset,
                                                user_data,
                                                page_length);
        else
                ret = __copy_from_user(vaddr + shmem_page_offset,
                                       user_data,
                                       page_length);
        if (needs_clflush_after)
                shmem_clflush_swizzled_range(vaddr + shmem_page_offset,
                                             page_length,
                                             page_do_bit17_swizzling);
        kunmap(page);

        return ret ? -EFAULT : 0;
}

static int
i915_gem_shmem_pwrite(struct drm_device *dev,
                      struct drm_i915_gem_object *obj,
                      struct drm_i915_gem_pwrite *args,
                      struct drm_file *file)
{
        ssize_t remain;
        loff_t offset;
        char __user *user_data;
        int shmem_page_offset, page_length, ret = 0;
        int obj_do_bit17_swizzling, page_do_bit17_swizzling;
        int hit_slowpath = 0;
        int needs_clflush_after = 0;
        int needs_clflush_before = 0;
        struct sg_page_iter sg_iter;

        user_data = u64_to_user_ptr(args->data_ptr);
        remain = args->size;

        obj_do_bit17_swizzling = i915_gem_object_needs_bit17_swizzle(obj);

        if (obj->base.write_domain != I915_GEM_DOMAIN_CPU) {
                /* If we're not in the cpu write domain, set ourself into the gtt
                 * write domain and manually flush cachelines (if required). This
                 * optimizes for the case when the gpu will use the data
                 * right away and we therefore have to clflush anyway. */
                needs_clflush_after = cpu_write_needs_clflush(obj);
                ret = i915_gem_object_wait_rendering(obj, false);
                if (ret)
                        return ret;
        }
        /* Same trick applies to invalidate partially written cachelines read
         * before writing. */
        if ((obj->base.read_domains & I915_GEM_DOMAIN_CPU) == 0)
                needs_clflush_before =
                        !cpu_cache_is_coherent(dev, obj->cache_level);

        ret = i915_gem_object_get_pages(obj);
        if (ret)
                return ret;

        intel_fb_obj_invalidate(obj, ORIGIN_CPU);

        i915_gem_object_pin_pages(obj);

        offset = args->offset;
        obj->dirty = 1;

        for_each_sg_page(obj->pages->sgl, &sg_iter, obj->pages->nents,
                         offset >> PAGE_SHIFT) {
                struct page *page = sg_page_iter_page(&sg_iter);
                int partial_cacheline_write;

                if (remain <= 0)
                        break;

                /* Operation in this page
                 *
                 * shmem_page_offset = offset within page in shmem file
                 * page_length = bytes to copy for this page
                 */
                shmem_page_offset = offset_in_page(offset);

                page_length = remain;
                if ((shmem_page_offset + page_length) > PAGE_SIZE)
                        page_length = PAGE_SIZE - shmem_page_offset;

                /* If we don't overwrite a cacheline completely we need to be
                 * careful to have up-to-date data by first clflushing. Don't
                 * overcomplicate things and flush the entire patch. */
                partial_cacheline_write = needs_clflush_before &&
                        ((shmem_page_offset | page_length)
                                & (boot_cpu_data.x86_clflush_size - 1));

                page_do_bit17_swizzling = obj_do_bit17_swizzling &&
                        (page_to_phys(page) & (1 << 17)) != 0;

                ret = shmem_pwrite_fast(page, shmem_page_offset, page_length,
                                        user_data, page_do_bit17_swizzling,
                                        partial_cacheline_write,
                                        needs_clflush_after);
                if (ret == 0)
                        goto next_page;

                hit_slowpath = 1;
                mutex_unlock(&dev->struct_mutex);
                ret = shmem_pwrite_slow(page, shmem_page_offset, page_length,
                                        user_data, page_do_bit17_swizzling,
                                        partial_cacheline_write,
                                        needs_clflush_after);

                mutex_lock(&dev->struct_mutex);

                if (ret)
                        goto out;

next_page:
                remain -= page_length;
                user_data += page_length;
                offset += page_length;
        }

out:
        i915_gem_object_unpin_pages(obj);

        if (hit_slowpath) {
                /*
                 * Fixup: Flush cpu caches in case we didn't flush the dirty
                 * cachelines in-line while writing and the object moved
                 * out of the cpu write domain while we've dropped the lock.
                 */

                if (!needs_clflush_after &&
                    obj->base.write_domain != I915_GEM_DOMAIN_CPU) {
                        if (i915_gem_clflush_object(obj, obj->pin_display))
                                needs_clflush_after = true;
                }
        }

        if (needs_clflush_after)
                i915_gem_chipset_flush(dev);
        else
                obj->cache_dirty = true;

        intel_fb_obj_flush(obj, false, ORIGIN_CPU);
        return ret;
}

/**
 * Writes data to the object referenced by handle.
 *
 * On error, the contents of the buffer that were to be modified are undefined.
 */
int
i915_gem_pwrite_ioctl(struct drm_device *dev, void *data,
                      struct drm_file *file)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct drm_i915_gem_pwrite *args = data;
        struct drm_i915_gem_object *obj;
        int ret;

        if (args->size == 0)
                return 0;

        if (!access_ok(VERIFY_READ,
                       u64_to_user_ptr(args->data_ptr),
                       args->size))
                return -EFAULT;

        if (likely(!i915.prefault_disable)) {
                ret = fault_in_multipages_readable(u64_to_user_ptr(args->data_ptr),
                                                   args->size);
                if (ret)
                        return -EFAULT;
        }

        intel_runtime_pm_get(dev_priv);

        ret = i915_mutex_lock_interruptible(dev);
        if (ret)
                goto put_rpm;

        obj = to_intel_bo(drm_gem_object_lookup(file, args->handle));
        if (&obj->base == NULL) {
                ret = -ENOENT;
                goto unlock;
        }

        /* Bounds check destination. */
        if (args->offset > obj->base.size ||
            args->size > obj->base.size - args->offset) {
                ret = -EINVAL;
                goto out;
        }

        /* prime objects have no backing filp to GEM pread/pwrite
         * pages from.
         */
        if (!obj->base.filp) {
                ret = -EINVAL;
                goto out;
        }

        trace_i915_gem_object_pwrite(obj, args->offset, args->size);

        ret = -EFAULT;
        /* We can only do the GTT pwrite on untiled buffers, as otherwise
         * it would end up going through the fenced access, and we'll get
         * different detiling behavior between reading and writing.
         * pread/pwrite currently are reading and writing from the CPU
         * perspective, requiring manual detiling by the client.
         */
        if (obj->tiling_mode == I915_TILING_NONE &&
            obj->base.write_domain != I915_GEM_DOMAIN_CPU &&
            cpu_write_needs_clflush(obj)) {
                ret = i915_gem_gtt_pwrite_fast(dev, obj, args, file);
                /* Note that the gtt paths might fail with non-page-backed user
                 * pointers (e.g. gtt mappings when moving data between
                 * textures). Fallback to the shmem path in that case. */
        }

        if (ret == -EFAULT || ret == -ENOSPC) {
                if (obj->phys_handle)
                        ret = i915_gem_phys_pwrite(obj, args, file);
                else
                        ret = i915_gem_shmem_pwrite(dev, obj, args, file);
        }

out:
        drm_gem_object_unreference(&obj->base);
unlock:
        mutex_unlock(&dev->struct_mutex);
put_rpm:
        intel_runtime_pm_put(dev_priv);

        return ret;
}

static int
i915_gem_check_wedge(unsigned reset_counter, bool interruptible)
{
        if (__i915_terminally_wedged(reset_counter))
                return -EIO;

        if (__i915_reset_in_progress(reset_counter)) {
                /* Non-interruptible callers can't handle -EAGAIN, hence return
                 * -EIO unconditionally for these. */
                if (!interruptible)
                        return -EIO;

                return -EAGAIN;
        }

        return 0;
}

static void fake_irq(unsigned long data)
{
        wake_up_process((struct task_struct *)data);
}

static bool missed_irq(struct drm_i915_private *dev_priv,
                       struct intel_engine_cs *engine)
{
        return test_bit(engine->id, &dev_priv->gpu_error.missed_irq_rings);
}

static unsigned long local_clock_us(unsigned *cpu)
{
        unsigned long t;

        /* Cheaply and approximately convert from nanoseconds to microseconds.
         * The result and subsequent calculations are also defined in the same
         * approximate microseconds units. The principal source of timing
         * error here is from the simple truncation.
         *
         * Note that local_clock() is only defined wrt to the current CPU;
         * the comparisons are no longer valid if we switch CPUs. Instead of
         * blocking preemption for the entire busywait, we can detect the CPU
         * switch and use that as indicator of system load and a reason to
         * stop busywaiting, see busywait_stop().
         */
        *cpu = get_cpu();
        t = local_clock() >> 10;
        put_cpu();

        return t;
}

static bool busywait_stop(unsigned long timeout, unsigned cpu)
{
        unsigned this_cpu;

        if (time_after(local_clock_us(&this_cpu), timeout))
                return true;

        return this_cpu != cpu;
}

static int __i915_spin_request(struct drm_i915_gem_request *req, int state)
{
        unsigned long timeout;
        unsigned cpu;

        /* When waiting for high frequency requests, e.g. during synchronous
         * rendering split between the CPU and GPU, the finite amount of time
         * required to set up the irq and wait upon it limits the response
         * rate. By busywaiting on the request completion for a short while we
         * can service the high frequency waits as quick as possible. However,
         * if it is a slow request, we want to sleep as quickly as possible.
         * The tradeoff between waiting and sleeping is roughly the time it
         * takes to sleep on a request, on the order of a microsecond.
         */

        if (req->engine->irq_refcount)
                return -EBUSY;

        /* Only spin if we know the GPU is processing this request */
        if (!i915_gem_request_started(req, true))
                return -EAGAIN;

        timeout = local_clock_us(&cpu) + 5;
        while (!need_resched()) {
                if (i915_gem_request_completed(req, true))
                        return 0;

                if (signal_pending_state(state, current))
                        break;

                if (busywait_stop(timeout, cpu))
                        break;

                cpu_relax_lowlatency();
        }

        if (i915_gem_request_completed(req, false))
                return 0;

        return -EAGAIN;
}

/**
 * __i915_wait_request - wait until execution of request has finished
 * @req: duh!
 * @interruptible: do an interruptible wait (normally yes)
 * @timeout: in - how long to wait (NULL forever); out - how much time remaining
 *
 * Note: It is of utmost importance that the passed in seqno and reset_counter
 * values have been read by the caller in an smp safe manner. Where read-side
 * locks are involved, it is sufficient to read the reset_counter before
 * unlocking the lock that protects the seqno. For lockless tricks, the
 * reset_counter _must_ be read before, and an appropriate smp_rmb must be
 * inserted.
 *
 * Returns 0 if the request was found within the alloted time. Else returns the
 * errno with remaining time filled in timeout argument.
 */
int __i915_wait_request(struct drm_i915_gem_request *req,
                        bool interruptible,
                        s64 *timeout,
                        struct intel_rps_client *rps)
{
        struct intel_engine_cs *engine = i915_gem_request_get_engine(req);
        struct drm_device *dev = engine->dev;
        struct drm_i915_private *dev_priv = dev->dev_private;
        const bool irq_test_in_progress =
                ACCESS_ONCE(dev_priv->gpu_error.test_irq_rings) & intel_engine_flag(engine);
        int state = interruptible ? TASK_INTERRUPTIBLE : TASK_UNINTERRUPTIBLE;
        DEFINE_WAIT(wait);
        unsigned long timeout_expire;
        s64 before = 0; /* Only to silence a compiler warning. */
        int ret;

        WARN(!intel_irqs_enabled(dev_priv), "IRQs disabled");

        if (list_empty(&req->list))
                return 0;

        if (i915_gem_request_completed(req, true))
                return 0;

        timeout_expire = 0;
        if (timeout) {
                if (WARN_ON(*timeout < 0))
                        return -EINVAL;

                if (*timeout == 0)
                        return -ETIME;

                timeout_expire = jiffies + nsecs_to_jiffies_timeout(*timeout);

                /*
                 * Record current time in case interrupted by signal, or wedged.
                 */
                before = ktime_get_raw_ns();
        }

        if (INTEL_INFO(dev_priv)->gen >= 6)
                gen6_rps_boost(dev_priv, rps, req->emitted_jiffies);

        trace_i915_gem_request_wait_begin(req);

        /* Optimistic spin for the next jiffie before touching IRQs */
        ret = __i915_spin_request(req, state);
        if (ret == 0)
                goto out;

        if (!irq_test_in_progress && WARN_ON(!engine->irq_get(engine))) {
                ret = -ENODEV;
                goto out;
        }

        for (;;) {
                struct timer_list timer;

                prepare_to_wait(&engine->irq_queue, &wait, state);

                /* We need to check whether any gpu reset happened in between
                 * the request being submitted and now. If a reset has occurred,
                 * the request is effectively complete (we either are in the
                 * process of or have discarded the rendering and completely
                 * reset the GPU. The results of the request are lost and we
                 * are free to continue on with the original operation.
                 */
                if (req->reset_counter != i915_reset_counter(&dev_priv->gpu_error)) {
                        ret = 0;
                        break;
                }

                if (i915_gem_request_completed(req, false)) {
                        ret = 0;
                        break;
                }

                if (signal_pending_state(state, current)) {
                        ret = -ERESTARTSYS;
                        break;
                }

                if (timeout && time_after_eq(jiffies, timeout_expire)) {
                        ret = -ETIME;
                        break;
                }

                timer.function = NULL;
                if (timeout || missed_irq(dev_priv, engine)) {
                        unsigned long expire;

                        setup_timer_on_stack(&timer, fake_irq, (unsigned long)current);
                        expire = missed_irq(dev_priv, engine) ? jiffies + 1 : timeout_expire;
                        mod_timer(&timer, expire);
                }

                io_schedule();

                if (timer.function) {
                        del_singleshot_timer_sync(&timer);
                        destroy_timer_on_stack(&timer);
                }
        }
        if (!irq_test_in_progress)
                engine->irq_put(engine);

        finish_wait(&engine->irq_queue, &wait);

out:
        trace_i915_gem_request_wait_end(req);

        if (timeout) {
                s64 tres = *timeout - (ktime_get_raw_ns() - before);

                *timeout = tres < 0 ? 0 : tres;

                /*
                 * Apparently ktime isn't accurate enough and occasionally has a
                 * bit of mismatch in the jiffies<->nsecs<->ktime loop. So patch
                 * things up to make the test happy. We allow up to 1 jiffy.
                 *
                 * This is a regrssion from the timespec->ktime conversion.
                 */
                if (ret == -ETIME && *timeout < jiffies_to_usecs(1)*1000)
                        *timeout = 0;
        }

        return ret;
}

int i915_gem_request_add_to_client(struct drm_i915_gem_request *req,
                                   struct drm_file *file)
{
        struct drm_i915_file_private *file_priv;

        WARN_ON(!req || !file || req->file_priv);

        if (!req || !file)
                return -EINVAL;

        if (req->file_priv)
                return -EINVAL;

        file_priv = file->driver_priv;

        spin_lock(&file_priv->mm.lock);
        req->file_priv = file_priv;
        list_add_tail(&req->client_list, &file_priv->mm.request_list);
        spin_unlock(&file_priv->mm.lock);

        req->pid = get_pid(task_pid(current));

        return 0;
}

static inline void
i915_gem_request_remove_from_client(struct drm_i915_gem_request *request)
{
        struct drm_i915_file_private *file_priv = request->file_priv;

        if (!file_priv)
                return;

        spin_lock(&file_priv->mm.lock);
        list_del(&request->client_list);
        request->file_priv = NULL;
        spin_unlock(&file_priv->mm.lock);

        put_pid(request->pid);
        request->pid = NULL;
}

static void i915_gem_request_retire(struct drm_i915_gem_request *request)
{
        trace_i915_gem_request_retire(request);

        /* We know the GPU must have read the request to have
         * sent us the seqno + interrupt, so use the position
         * of tail of the request to update the last known position
         * of the GPU head.
         *
         * Note this requires that we are always called in request
         * completion order.
         */
        request->ringbuf->last_retired_head = request->postfix;

        list_del_init(&request->list);
        i915_gem_request_remove_from_client(request);

        i915_gem_request_unreference(request);
}

static void
__i915_gem_request_retire__upto(struct drm_i915_gem_request *req)
{
        struct intel_engine_cs *engine = req->engine;
        struct drm_i915_gem_request *tmp;

        lockdep_assert_held(&engine->dev->struct_mutex);

        if (list_empty(&req->list))
                return;

        do {
                tmp = list_first_entry(&engine->request_list,
                                       typeof(*tmp), list);

                i915_gem_request_retire(tmp);
        } while (tmp != req);

        WARN_ON(i915_verify_lists(engine->dev));
}

/**
 * Waits for a request to be signaled, and cleans up the
 * request and object lists appropriately for that event.
 */
int
i915_wait_request(struct drm_i915_gem_request *req)
{
        struct drm_i915_private *dev_priv = req->i915;
        bool interruptible;
        int ret;

        interruptible = dev_priv->mm.interruptible;

        BUG_ON(!mutex_is_locked(&dev_priv->dev->struct_mutex));

        ret = __i915_wait_request(req, interruptible, NULL, NULL);
        if (ret)
                return ret;

        /* If the GPU hung, we want to keep the requests to find the guilty. */
        if (req->reset_counter == i915_reset_counter(&dev_priv->gpu_error))
                __i915_gem_request_retire__upto(req);

        return 0;
}

/**
 * Ensures that all rendering to the object has completed and the object is
 * safe to unbind from the GTT or access from the CPU.
 */
int
i915_gem_object_wait_rendering(struct drm_i915_gem_object *obj,
                               bool readonly)
{
        int ret, i;

        if (!obj->active)
                return 0;

        if (readonly) {
                if (obj->last_write_req != NULL) {
                        ret = i915_wait_request(obj->last_write_req);
                        if (ret)
                                return ret;

                        i = obj->last_write_req->engine->id;
                        if (obj->last_read_req[i] == obj->last_write_req)
                                i915_gem_object_retire__read(obj, i);
                        else
                                i915_gem_object_retire__write(obj);
                }
        } else {
                for (i = 0; i < I915_NUM_ENGINES; i++) {
                        if (obj->last_read_req[i] == NULL)
                                continue;

                        ret = i915_wait_request(obj->last_read_req[i]);
                        if (ret)
                                return ret;

                        i915_gem_object_retire__read(obj, i);
                }
                GEM_BUG_ON(obj->active);
        }

        return 0;
}

static void
i915_gem_object_retire_request(struct drm_i915_gem_object *obj,
                               struct drm_i915_gem_request *req)
{
        int ring = req->engine->id;

        if (obj->last_read_req[ring] == req)
                i915_gem_object_retire__read(obj, ring);
        else if (obj->last_write_req == req)
                i915_gem_object_retire__write(obj);

        if (req->reset_counter == i915_reset_counter(&req->i915->gpu_error))
                __i915_gem_request_retire__upto(req);
}

/* A nonblocking variant of the above wait. This is a highly dangerous routine
 * as the object state may change during this call.
 */
static __must_check int
i915_gem_object_wait_rendering__nonblocking(struct drm_i915_gem_object *obj,
                                            struct intel_rps_client *rps,
                                            bool readonly)
{
        struct drm_device *dev = obj->base.dev;
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct drm_i915_gem_request *requests[I915_NUM_ENGINES];
        int ret, i, n = 0;

        BUG_ON(!mutex_is_locked(&dev->struct_mutex));
        BUG_ON(!dev_priv->mm.interruptible);

        if (!obj->active)
                return 0;

        if (readonly) {
                struct drm_i915_gem_request *req;

                req = obj->last_write_req;
                if (req == NULL)
                        return 0;

                requests[n++] = i915_gem_request_reference(req);
        } else {
                for (i = 0; i < I915_NUM_ENGINES; i++) {
                        struct drm_i915_gem_request *req;

                        req = obj->last_read_req[i];
                        if (req == NULL)
                                continue;

                        requests[n++] = i915_gem_request_reference(req);
                }
        }

        mutex_unlock(&dev->struct_mutex);
        ret = 0;
        for (i = 0; ret == 0 && i < n; i++)
                ret = __i915_wait_request(requests[i], true, NULL, rps);
        mutex_lock(&dev->struct_mutex);

        for (i = 0; i < n; i++) {
                if (ret == 0)
                        i915_gem_object_retire_request(obj, requests[i]);
                i915_gem_request_unreference(requests[i]);
        }

        return ret;
}

static struct intel_rps_client *to_rps_client(struct drm_file *file)
{
        struct drm_i915_file_private *fpriv = file->driver_priv;
        return &fpriv->rps;
}

/**
 * Called when user space prepares to use an object with the CPU, either
 * through the mmap ioctl's mapping or a GTT mapping.
 */
int
i915_gem_set_domain_ioctl(struct drm_device *dev, void *data,
                          struct drm_file *file)
{
        struct drm_i915_gem_set_domain *args = data;
        struct drm_i915_gem_object *obj;
        uint32_t read_domains = args->read_domains;
        uint32_t write_domain = args->write_domain;
        int ret;

        /* Only handle setting domains to types used by the CPU. */
        if (write_domain & I915_GEM_GPU_DOMAINS)
                return -EINVAL;

        if (read_domains & I915_GEM_GPU_DOMAINS)
                return -EINVAL;

        /* Having something in the write domain implies it's in the read
         * domain, and only that read domain.  Enforce that in the request.
         */
        if (write_domain != 0 && read_domains != write_domain)
                return -EINVAL;

        ret = i915_mutex_lock_interruptible(dev);
        if (ret)
                return ret;

        obj = to_intel_bo(drm_gem_object_lookup(file, args->handle));
        if (&obj->base == NULL) {
                ret = -ENOENT;
                goto unlock;
        }

        /* Try to flush the object off the GPU without holding the lock.
         * We will repeat the flush holding the lock in the normal manner
         * to catch cases where we are gazumped.
         */
        ret = i915_gem_object_wait_rendering__nonblocking(obj,
                                                          to_rps_client(file),
                                                          !write_domain);
        if (ret)
                goto unref;

        if (read_domains & I915_GEM_DOMAIN_GTT)
                ret = i915_gem_object_set_to_gtt_domain(obj, write_domain != 0);
        else
                ret = i915_gem_object_set_to_cpu_domain(obj, write_domain != 0);

        if (write_domain != 0)
                intel_fb_obj_invalidate(obj,
                                        write_domain == I915_GEM_DOMAIN_GTT ?
                                        ORIGIN_GTT : ORIGIN_CPU);

unref:
        drm_gem_object_unreference(&obj->base);
unlock:
        mutex_unlock(&dev->struct_mutex);
        return ret;
}

/**
 * Called when user space has done writes to this buffer
 */
int
i915_gem_sw_finish_ioctl(struct drm_device *dev, void *data,
                         struct drm_file *file)
{
        struct drm_i915_gem_sw_finish *args = data;
        struct drm_i915_gem_object *obj;
        int ret = 0;

        ret = i915_mutex_lock_interruptible(dev);
        if (ret)
                return ret;

        obj = to_intel_bo(drm_gem_object_lookup(file, args->handle));
        if (&obj->base == NULL) {
                ret = -ENOENT;
                goto unlock;
        }

        /* Pinned buffers may be scanout, so flush the cache */
        if (obj->pin_display)
                i915_gem_object_flush_cpu_write_domain(obj);

        drm_gem_object_unreference(&obj->base);
unlock:
        mutex_unlock(&dev->struct_mutex);
        return ret;
}

/**
 * Maps the contents of an object, returning the address it is mapped
 * into.
 *
 * While the mapping holds a reference on the contents of the object, it doesn't
 * imply a ref on the object itself.
 *
 * IMPORTANT:
 *
 * DRM driver writers who look a this function as an example for how to do GEM
 * mmap support, please don't implement mmap support like here. The modern way
 * to implement DRM mmap support is with an mmap offset ioctl (like
 * i915_gem_mmap_gtt) and then using the mmap syscall on the DRM fd directly.
 * That way debug tooling like valgrind will understand what's going on, hiding
 * the mmap call in a driver private ioctl will break that. The i915 driver only
 * does cpu mmaps this way because we didn't know better.
 */
int
i915_gem_mmap_ioctl(struct drm_device *dev, void *data,
                    struct drm_file *file)
{
        struct drm_i915_gem_mmap *args = data;
        struct drm_gem_object *obj;
        unsigned long addr;

        if (args->flags & ~(I915_MMAP_WC))
                return -EINVAL;

        if (args->flags & I915_MMAP_WC && !boot_cpu_has(X86_FEATURE_PAT))
                return -ENODEV;

        obj = drm_gem_object_lookup(file, args->handle);
        if (obj == NULL)
                return -ENOENT;

        /* prime objects have no backing filp to GEM mmap
         * pages from.
         */
        if (!obj->filp) {
                drm_gem_object_unreference_unlocked(obj);
                return -EINVAL;
        }

        addr = vm_mmap(obj->filp, 0, args->size,
                       PROT_READ | PROT_WRITE, MAP_SHARED,
                       args->offset);
        if (args->flags & I915_MMAP_WC) {
                struct mm_struct *mm = current->mm;
                struct vm_area_struct *vma;

                if (down_write_killable(&mm->mmap_sem)) {
                        drm_gem_object_unreference_unlocked(obj);
                        return -EINTR;
                }
                vma = find_vma(mm, addr);
                if (vma)
                        vma->vm_page_prot =
                                pgprot_writecombine(vm_get_page_prot(vma->vm_flags));
                else
                        addr = -ENOMEM;
                up_write(&mm->mmap_sem);
        }
        drm_gem_object_unreference_unlocked(obj);
        if (IS_ERR((void *)addr))
                return addr;

        args->addr_ptr = (uint64_t) addr;

        return 0;
}

/**
 * i915_gem_fault - fault a page into the GTT
 * @vma: VMA in question
 * @vmf: fault info
 *
 * The fault handler is set up by drm_gem_mmap() when a object is GTT mapped
 * from userspace.  The fault handler takes care of binding the object to
 * the GTT (if needed), allocating and programming a fence register (again,
 * only if needed based on whether the old reg is still valid or the object
 * is tiled) and inserting a new PTE into the faulting process.
 *
 * Note that the faulting process may involve evicting existing objects
 * from the GTT and/or fence registers to make room.  So performance may
 * suffer if the GTT working set is large or there are few fence registers
 * left.
 */
int i915_gem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
        struct drm_i915_gem_object *obj = to_intel_bo(vma->vm_private_data);
        struct drm_device *dev = obj->base.dev;
        struct drm_i915_private *dev_priv = to_i915(dev);
        struct i915_ggtt *ggtt = &dev_priv->ggtt;
        struct i915_ggtt_view view = i915_ggtt_view_normal;
        pgoff_t page_offset;
        unsigned long pfn;
        int ret = 0;
        bool write = !!(vmf->flags & FAULT_FLAG_WRITE);

        intel_runtime_pm_get(dev_priv);

        /* We don't use vmf->pgoff since that has the fake offset */
        page_offset = ((unsigned long)vmf->virtual_address - vma->vm_start) >>
                PAGE_SHIFT;

        ret = i915_mutex_lock_interruptible(dev);
        if (ret)
                goto out;

        trace_i915_gem_object_fault(obj, page_offset, true, write);

        /* Try to flush the object off the GPU first without holding the lock.
         * Upon reacquiring the lock, we will perform our sanity checks and then
         * repeat the flush holding the lock in the normal manner to catch cases
         * where we are gazumped.
         */
        ret = i915_gem_object_wait_rendering__nonblocking(obj, NULL, !write);
        if (ret)
                goto unlock;

        /* Access to snoopable pages through the GTT is incoherent. */
        if (obj->cache_level != I915_CACHE_NONE && !HAS_LLC(dev)) {
                ret = -EFAULT;
                goto unlock;
        }

        /* Use a partial view if the object is bigger than the aperture. */
        if (obj->base.size >= ggtt->mappable_end &&
            obj->tiling_mode == I915_TILING_NONE) {
                static const unsigned int chunk_size = 256; // 1 MiB

                memset(&view, 0, sizeof(view));
                view.type = I915_GGTT_VIEW_PARTIAL;
                view.params.partial.offset = rounddown(page_offset, chunk_size);
                view.params.partial.size =
                        min_t(unsigned int,
                              chunk_size,
                              (vma->vm_end - vma->vm_start)/PAGE_SIZE -
                              view.params.partial.offset);
        }

        /* Now pin it into the GTT if needed */
        ret = i915_gem_object_ggtt_pin(obj, &view, 0, PIN_MAPPABLE);
        if (ret)
                goto unlock;

        ret = i915_gem_object_set_to_gtt_domain(obj, write);
        if (ret)
                goto unpin;

        ret = i915_gem_object_get_fence(obj);
        if (ret)
                goto unpin;

        /* Finally, remap it using the new GTT offset */
        pfn = ggtt->mappable_base +
                i915_gem_obj_ggtt_offset_view(obj, &view);
        pfn >>= PAGE_SHIFT;

        if (unlikely(view.type == I915_GGTT_VIEW_PARTIAL)) {
                /* Overriding existing pages in partial view does not cause
                 * us any trouble as TLBs are still valid because the fault
                 * is due to userspace losing part of the mapping or never
                 * having accessed it before (at this partials' range).
                 */
                unsigned long base = vma->vm_start +
                                     (view.params.partial.offset << PAGE_SHIFT);
                unsigned int i;

                for (i = 0; i < view.params.partial.size; i++) {
                        ret = vm_insert_pfn(vma, base + i * PAGE_SIZE, pfn + i);
                        if (ret)
                                break;
                }

                obj->fault_mappable = true;
        } else {
                if (!obj->fault_mappable) {
                        unsigned long size = min_t(unsigned long,
                                                   vma->vm_end - vma->vm_start,
                                                   obj->base.size);
                        int i;

                        for (i = 0; i < size >> PAGE_SHIFT; i++) {
                                ret = vm_insert_pfn(vma,
                                                    (unsigned long)vma->vm_start + i * PAGE_SIZE,
                                                    pfn + i);
                                if (ret)
                                        break;
                        }

                        obj->fault_mappable = true;
                } else
                        ret = vm_insert_pfn(vma,
                                            (unsigned long)vmf->virtual_address,
                                            pfn + page_offset);
        }
unpin:
        i915_gem_object_ggtt_unpin_view(obj, &view);
unlock:
        mutex_unlock(&dev->struct_mutex);
out:
        switch (ret) {
        case -EIO:
                /*
                 * We eat errors when the gpu is terminally wedged to avoid
                 * userspace unduly crashing (gl has no provisions for mmaps to
                 * fail). But any other -EIO isn't ours (e.g. swap in failure)
                 * and so needs to be reported.
                 */
                if (!i915_terminally_wedged(&dev_priv->gpu_error)) {
                        ret = VM_FAULT_SIGBUS;
                        break;
                }
        case -EAGAIN:
                /*
                 * EAGAIN means the gpu is hung and we'll wait for the error
                 * handler to reset everything when re-faulting in
                 * i915_mutex_lock_interruptible.
                 */
        case 0:
        case -ERESTARTSYS:
        case -EINTR:
        case -EBUSY:
                /*
                 * EBUSY is ok: this just means that another thread
                 * already did the job.
                 */
                ret = VM_FAULT_NOPAGE;
                break;
        case -ENOMEM:
                ret = VM_FAULT_OOM;
                break;
        case -ENOSPC:
        case -EFAULT:
                ret = VM_FAULT_SIGBUS;
                break;
        default:
                WARN_ONCE(ret, "unhandled error in i915_gem_fault: %i\n", ret);
                ret = VM_FAULT_SIGBUS;
                break;
        }

        intel_runtime_pm_put(dev_priv);
        return ret;
}

/**
 * i915_gem_release_mmap - remove physical page mappings
 * @obj: obj in question
 *
 * Preserve the reservation of the mmapping with the DRM core code, but
 * relinquish ownership of the pages back to the system.
 *
 * It is vital that we remove the page mapping if we have mapped a tiled
 * object through the GTT and then lose the fence register due to
 * resource pressure. Similarly if the object has been moved out of the
 * aperture, than pages mapped into userspace must be revoked. Removing the
 * mapping will then trigger a page fault on the next user access, allowing
 * fixup by i915_gem_fault().
 */
void
i915_gem_release_mmap(struct drm_i915_gem_object *obj)
{
        /* Serialisation between user GTT access and our code depends upon
         * revoking the CPU's PTE whilst the mutex is held. The next user
         * pagefault then has to wait until we release the mutex.
         */
        lockdep_assert_held(&obj->base.dev->struct_mutex);

        if (!obj->fault_mappable)
                return;

        drm_vma_node_unmap(&obj->base.vma_node,
                           obj->base.dev->anon_inode->i_mapping);

        /* Ensure that the CPU's PTE are revoked and there are not outstanding
         * memory transactions from userspace before we return. The TLB
         * flushing implied above by changing the PTE above *should* be
         * sufficient, an extra barrier here just provides us with a bit
         * of paranoid documentation about our requirement to serialise
         * memory writes before touching registers / GSM.
         */
        wmb();

        obj->fault_mappable = false;
}

void
i915_gem_release_all_mmaps(struct drm_i915_private *dev_priv)
{
        struct drm_i915_gem_object *obj;

        list_for_each_entry(obj, &dev_priv->mm.bound_list, global_list)
                i915_gem_release_mmap(obj);
}

uint32_t
i915_gem_get_gtt_size(struct drm_device *dev, uint32_t size, int tiling_mode)
{
        uint32_t gtt_size;

        if (INTEL_INFO(dev)->gen >= 4 ||
            tiling_mode == I915_TILING_NONE)
                return size;

        /* Previous chips need a power-of-two fence region when tiling */
        if (INTEL_INFO(dev)->gen == 3)
                gtt_size = 1024*1024;
        else
                gtt_size = 512*1024;

        while (gtt_size < size)
                gtt_size <<= 1;

        return gtt_size;
}

/**
 * i915_gem_get_gtt_alignment - return required GTT alignment for an object
 * @obj: object to check
 *
 * Return the required GTT alignment for an object, taking into account

 * potential fence register mapping.
 */
uint32_t
i915_gem_get_gtt_alignment(struct drm_device *dev, uint32_t size,
                           int tiling_mode, bool fenced)
{
        /*
         * Minimum alignment is 4k (GTT page size), but might be greater
         * if a fence register is needed for the object.
         */
        if (INTEL_INFO(dev)->gen >= 4 || (!fenced && IS_G33(dev)) ||
            tiling_mode == I915_TILING_NONE)
                return 4096;

        /*
         * Previous chips need to be aligned to the size of the smallest
         * fence register that can contain the object.
         */
        return i915_gem_get_gtt_size(dev, size, tiling_mode);
}

static int i915_gem_object_create_mmap_offset(struct drm_i915_gem_object *obj)
{
        struct drm_i915_private *dev_priv = obj->base.dev->dev_private;
        int ret;

        dev_priv->mm.shrinker_no_lock_stealing = true;

        ret = drm_gem_create_mmap_offset(&obj->base);
        if (ret != -ENOSPC)
                goto out;

        /* Badly fragmented mmap space? The only way we can recover
         * space is by destroying unwanted objects. We can't randomly release
         * mmap_offsets as userspace expects them to be persistent for the
         * lifetime of the objects. The closest we can is to release the
         * offsets on purgeable objects by truncating it and marking it purged,
         * which prevents userspace from ever using that object again.
         */
        i915_gem_shrink(dev_priv,
                        obj->base.size >> PAGE_SHIFT,
                        I915_SHRINK_BOUND |
                        I915_SHRINK_UNBOUND |
                        I915_SHRINK_PURGEABLE);
        ret = drm_gem_create_mmap_offset(&obj->base);
        if (ret != -ENOSPC)
                goto out;

        i915_gem_shrink_all(dev_priv);
        ret = drm_gem_create_mmap_offset(&obj->base);
out:
        dev_priv->mm.shrinker_no_lock_stealing = false;

        return ret;
}

static void i915_gem_object_free_mmap_offset(struct drm_i915_gem_object *obj)
{
        drm_gem_free_mmap_offset(&obj->base);
}

int
i915_gem_mmap_gtt(struct drm_file *file,
                  struct drm_device *dev,
                  uint32_t handle,
                  uint64_t *offset)
{
        struct drm_i915_gem_object *obj;
        int ret;

        ret = i915_mutex_lock_interruptible(dev);
        if (ret)
                return ret;

        obj = to_intel_bo(drm_gem_object_lookup(file, handle));
        if (&obj->base == NULL) {
                ret = -ENOENT;
                goto unlock;
        }

        if (obj->madv != I915_MADV_WILLNEED) {
                DRM_DEBUG("Attempting to mmap a purgeable buffer\n");
                ret = -EFAULT;
                goto out;
        }

        ret = i915_gem_object_create_mmap_offset(obj);
        if (ret)
                goto out;

        *offset = drm_vma_node_offset_addr(&obj->base.vma_node);

out:
        drm_gem_object_unreference(&obj->base);
unlock:
        mutex_unlock(&dev->struct_mutex);
        return ret;
}

/**
 * i915_gem_mmap_gtt_ioctl - prepare an object for GTT mmap'ing
 * @dev: DRM device
 * @data: GTT mapping ioctl data
 * @file: GEM object info
 *
 * Simply returns the fake offset to userspace so it can mmap it.
 * The mmap call will end up in drm_gem_mmap(), which will set things
 * up so we can get faults in the handler above.
 *
 * The fault handler will take care of binding the object into the GTT
 * (since it may have been evicted to make room for something), allocating
 * a fence register, and mapping the appropriate aperture address into
 * userspace.
 */
int
i915_gem_mmap_gtt_ioctl(struct drm_device *dev, void *data,
                        struct drm_file *file)
{
        struct drm_i915_gem_mmap_gtt *args = data;

        return i915_gem_mmap_gtt(file, dev, args->handle, &args->offset);
}

/* Immediately discard the backing storage */
static void
i915_gem_object_truncate(struct drm_i915_gem_object *obj)
{
        i915_gem_object_free_mmap_offset(obj);

        if (obj->base.filp == NULL)
                return;

        /* Our goal here is to return as much of the memory as
         * is possible back to the system as we are called from OOM.
         * To do this we must instruct the shmfs to drop all of its
         * backing pages, *now*.
         */
        shmem_truncate_range(file_inode(obj->base.filp), 0, (loff_t)-1);
        obj->madv = __I915_MADV_PURGED;
}

/* Try to discard unwanted pages */
static void
i915_gem_object_invalidate(struct drm_i915_gem_object *obj)
{
        struct address_space *mapping;

        switch (obj->madv) {
        case I915_MADV_DONTNEED:
                i915_gem_object_truncate(obj);
        case __I915_MADV_PURGED:
                return;
        }

        if (obj->base.filp == NULL)
                return;

        mapping = file_inode(obj->base.filp)->i_mapping,
        invalidate_mapping_pages(mapping, 0, (loff_t)-1);
}

static void
i915_gem_object_put_pages_gtt(struct drm_i915_gem_object *obj)
{
        struct sg_page_iter sg_iter;
        int ret;

        BUG_ON(obj->madv == __I915_MADV_PURGED);

        ret = i915_gem_object_set_to_cpu_domain(obj, true);
        if (WARN_ON(ret)) {
                /* In the event of a disaster, abandon all caches and
                 * hope for the best.
                 */
                i915_gem_clflush_object(obj, true);
                obj->base.read_domains = obj->base.write_domain = I915_GEM_DOMAIN_CPU;
        }

        i915_gem_gtt_finish_object(obj);

        if (i915_gem_object_needs_bit17_swizzle(obj))
                i915_gem_object_save_bit_17_swizzle(obj);

        if (obj->madv == I915_MADV_DONTNEED)
                obj->dirty = 0;

        for_each_sg_page(obj->pages->sgl, &sg_iter, obj->pages->nents, 0) {
                struct page *page = sg_page_iter_page(&sg_iter);

                if (obj->dirty)
                        set_page_dirty(page);

                if (obj->madv == I915_MADV_WILLNEED)
                        mark_page_accessed(page);

                put_page(page);
        }
        obj->dirty = 0;

        sg_free_table(obj->pages);
        kfree(obj->pages);
}

int
i915_gem_object_put_pages(struct drm_i915_gem_object *obj)
{
        const struct drm_i915_gem_object_ops *ops = obj->ops;

        if (obj->pages == NULL)
                return 0;

        if (obj->pages_pin_count)
                return -EBUSY;

        BUG_ON(i915_gem_obj_bound_any(obj));

        /* ->put_pages might need to allocate memory for the bit17 swizzle
         * array, hence protect them from being reaped by removing them from gtt
         * lists early. */
        list_del(&obj->global_list);

        if (obj->mapping) {
                if (is_vmalloc_addr(obj->mapping))
                        vunmap(obj->mapping);
                else
                        kunmap(kmap_to_page(obj->mapping));
                obj->mapping = NULL;
        }

        ops->put_pages(obj);
        obj->pages = NULL;

        i915_gem_object_invalidate(obj);

        return 0;
}

static int
i915_gem_object_get_pages_gtt(struct drm_i915_gem_object *obj)
{
        struct drm_i915_private *dev_priv = obj->base.dev->dev_private;
        int page_count, i;
        struct address_space *mapping;
        struct sg_table *st;
        struct scatterlist *sg;
        struct sg_page_iter sg_iter;
        struct page *page;
        unsigned long last_pfn = 0;     /* suppress gcc warning */
        int ret;
        gfp_t gfp;

        /* Assert that the object is not currently in any GPU domain. As it
         * wasn't in the GTT, there shouldn't be any way it could have been in
         * a GPU cache
         */
        BUG_ON(obj->base.read_domains & I915_GEM_GPU_DOMAINS);
        BUG_ON(obj->base.write_domain & I915_GEM_GPU_DOMAINS);

        st = kmalloc(sizeof(*st), GFP_KERNEL);
        if (st == NULL)
                return -ENOMEM;

        page_count = obj->base.size / PAGE_SIZE;
        if (sg_alloc_table(st, page_count, GFP_KERNEL)) {
                kfree(st);
                return -ENOMEM;
        }

        /* Get the list of pages out of our struct file.  They'll be pinned
         * at this point until we release them.
         *
         * Fail silently without starting the shrinker
         */
        mapping = file_inode(obj->base.filp)->i_mapping;
        gfp = mapping_gfp_constraint(mapping, ~(__GFP_IO | __GFP_RECLAIM));
        gfp |= __GFP_NORETRY | __GFP_NOWARN;
        sg = st->sgl;
        st->nents = 0;
        for (i = 0; i < page_count; i++) {
                page = shmem_read_mapping_page_gfp(mapping, i, gfp);
                if (IS_ERR(page)) {
                        i915_gem_shrink(dev_priv,
                                        page_count,
                                        I915_SHRINK_BOUND |
                                        I915_SHRINK_UNBOUND |
                                        I915_SHRINK_PURGEABLE);
                        page = shmem_read_mapping_page_gfp(mapping, i, gfp);
                }
                if (IS_ERR(page)) {
                        /* We've tried hard to allocate the memory by reaping
                         * our own buffer, now let the real VM do its job and
                         * go down in flames if truly OOM.
                         */
                        i915_gem_shrink_all(dev_priv);
                        page = shmem_read_mapping_page(mapping, i);
                        if (IS_ERR(page)) {
                                ret = PTR_ERR(page);
                                goto err_pages;
                        }
                }
#ifdef CONFIG_SWIOTLB
                if (swiotlb_nr_tbl()) {
                        st->nents++;
                        sg_set_page(sg, page, PAGE_SIZE, 0);
                        sg = sg_next(sg);
                        continue;
                }
#endif
                if (!i || page_to_pfn(page) != last_pfn + 1) {
                        if (i)
                                sg = sg_next(sg);
                        st->nents++;
                        sg_set_page(sg, page, PAGE_SIZE, 0);
                } else {
                        sg->length += PAGE_SIZE;
                }
                last_pfn = page_to_pfn(page);

                /* Check that the i965g/gm workaround works. */
                WARN_ON((gfp & __GFP_DMA32) && (last_pfn >= 0x00100000UL));
        }
#ifdef CONFIG_SWIOTLB
        if (!swiotlb_nr_tbl())
#endif
                sg_mark_end(sg);
        obj->pages = st;

        ret = i915_gem_gtt_prepare_object(obj);
        if (ret)
                goto err_pages;

        if (i915_gem_object_needs_bit17_swizzle(obj))
                i915_gem_object_do_bit_17_swizzle(obj);

        if (obj->tiling_mode != I915_TILING_NONE &&
            dev_priv->quirks & QUIRK_PIN_SWIZZLED_PAGES)
                i915_gem_object_pin_pages(obj);

        return 0;

err_pages:
        sg_mark_end(sg);
        for_each_sg_page(st->sgl, &sg_iter, st->nents, 0)
                put_page(sg_page_iter_page(&sg_iter));
        sg_free_table(st);
        kfree(st);

        /* shmemfs first checks if there is enough memory to allocate the page
         * and reports ENOSPC should there be insufficient, along with the usual
         * ENOMEM for a genuine allocation failure.
         *
         * We use ENOSPC in our driver to mean that we have run out of aperture
         * space and so want to translate the error from shmemfs back to our
         * usual understanding of ENOMEM.
         */
        if (ret == -ENOSPC)
                ret = -ENOMEM;

        return ret;
}

/* Ensure that the associated pages are gathered from the backing storage
 * and pinned into our object. i915_gem_object_get_pages() may be called
 * multiple times before they are released by a single call to
 * i915_gem_object_put_pages() - once the pages are no longer referenced
 * either as a result of memory pressure (reaping pages under the shrinker)
 * or as the object is itself released.
 */
int
i915_gem_object_get_pages(struct drm_i915_gem_object *obj)
{
        struct drm_i915_private *dev_priv = obj->base.dev->dev_private;
        const struct drm_i915_gem_object_ops *ops = obj->ops;
        int ret;

        if (obj->pages)
                return 0;

        if (obj->madv != I915_MADV_WILLNEED) {
                DRM_DEBUG("Attempting to obtain a purgeable object\n");
                return -EFAULT;
        }

        BUG_ON(obj->pages_pin_count);

        ret = ops->get_pages(obj);
        if (ret)
                return ret;

        list_add_tail(&obj->global_list, &dev_priv->mm.unbound_list);

        obj->get_page.sg = obj->pages->sgl;
        obj->get_page.last = 0;

        return 0;
}

void *i915_gem_object_pin_map(struct drm_i915_gem_object *obj)
{
        int ret;

        lockdep_assert_held(&obj->base.dev->struct_mutex);

        ret = i915_gem_object_get_pages(obj);
        if (ret)
                return ERR_PTR(ret);

        i915_gem_object_pin_pages(obj);

        if (obj->mapping == NULL) {
                struct page **pages;

                pages = NULL;
                if (obj->base.size == PAGE_SIZE)
                        obj->mapping = kmap(sg_page(obj->pages->sgl));
                else
                        pages = drm_malloc_gfp(obj->base.size >> PAGE_SHIFT,
                                               sizeof(*pages),
                                               GFP_TEMPORARY);
                if (pages != NULL) {
                        struct sg_page_iter sg_iter;
                        int n;

                        n = 0;
                        for_each_sg_page(obj->pages->sgl, &sg_iter,
                                         obj->pages->nents, 0)
                                pages[n++] = sg_page_iter_page(&sg_iter);

                        obj->mapping = vmap(pages, n, 0, PAGE_KERNEL);
                        drm_free_large(pages);
                }
                if (obj->mapping == NULL) {
                        i915_gem_object_unpin_pages(obj);
                        return ERR_PTR(-ENOMEM);
                }
        }

        return obj->mapping;
}

void i915_vma_move_to_active(struct i915_vma *vma,
                             struct drm_i915_gem_request *req)
{
        struct drm_i915_gem_object *obj = vma->obj;
        struct intel_engine_cs *engine;

        engine = i915_gem_request_get_engine(req);

        /* Add a reference if we're newly entering the active list. */
        if (obj->active == 0)
                drm_gem_object_reference(&obj->base);
        obj->active |= intel_engine_flag(engine);

        list_move_tail(&obj->engine_list[engine->id], &engine->active_list);
        i915_gem_request_assign(&obj->last_read_req[engine->id], req);

        list_move_tail(&vma->vm_link, &vma->vm->active_list);
}

static void
i915_gem_object_retire__write(struct drm_i915_gem_object *obj)
{
        GEM_BUG_ON(obj->last_write_req == NULL);
        GEM_BUG_ON(!(obj->active & intel_engine_flag(obj->last_write_req->engine)));

        i915_gem_request_assign(&obj->last_write_req, NULL);
        intel_fb_obj_flush(obj, true, ORIGIN_CS);
}

static void
i915_gem_object_retire__read(struct drm_i915_gem_object *obj, int ring)
{
        struct i915_vma *vma;

        GEM_BUG_ON(obj->last_read_req[ring] == NULL);
        GEM_BUG_ON(!(obj->active & (1 << ring)));

        list_del_init(&obj->engine_list[ring]);
        i915_gem_request_assign(&obj->last_read_req[ring], NULL);

        if (obj->last_write_req && obj->last_write_req->engine->id == ring)
                i915_gem_object_retire__write(obj);

        obj->active &= ~(1 << ring);
        if (obj->active)
                return;

        /* Bump our place on the bound list to keep it roughly in LRU order
         * so that we don't steal from recently used but inactive objects
         * (unless we are forced to ofc!)
         */
        list_move_tail(&obj->global_list,
                       &to_i915(obj->base.dev)->mm.bound_list);

        list_for_each_entry(vma, &obj->vma_list, obj_link) {
                if (!list_empty(&vma->vm_link))
                        list_move_tail(&vma->vm_link, &vma->vm->inactive_list);
        }

        i915_gem_request_assign(&obj->last_fenced_req, NULL);
        drm_gem_object_unreference(&obj->base);
}

static int
i915_gem_init_seqno(struct drm_device *dev, u32 seqno)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct intel_engine_cs *engine;
        int ret;

        /* Carefully retire all requests without writing to the rings */
        for_each_engine(engine, dev_priv) {
                ret = intel_engine_idle(engine);
                if (ret)
                        return ret;
        }
        i915_gem_retire_requests(dev);

        /* Finally reset hw state */
        for_each_engine(engine, dev_priv)
                intel_ring_init_seqno(engine, seqno);

        return 0;
}

int i915_gem_set_seqno(struct drm_device *dev, u32 seqno)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        int ret;

        if (seqno == 0)
                return -EINVAL;

        /* HWS page needs to be set less than what we
         * will inject to ring
         */
        ret = i915_gem_init_seqno(dev, seqno - 1);
        if (ret)
                return ret;

        /* Carefully set the last_seqno value so that wrap
         * detection still works
         */
        dev_priv->next_seqno = seqno;
        dev_priv->last_seqno = seqno - 1;
        if (dev_priv->last_seqno == 0)
                dev_priv->last_seqno--;

        return 0;
}

int
i915_gem_get_seqno(struct drm_device *dev, u32 *seqno)
{
        struct drm_i915_private *dev_priv = dev->dev_private;

        /* reserve 0 for non-seqno */
        if (dev_priv->next_seqno == 0) {
                int ret = i915_gem_init_seqno(dev, 0);
                if (ret)
                        return ret;

                dev_priv->next_seqno = 1;
        }

        *seqno = dev_priv->last_seqno = dev_priv->next_seqno++;
        return 0;
}

/*
 * NB: This function is not allowed to fail. Doing so would mean the the
 * request is not being tracked for completion but the work itself is
 * going to happen on the hardware. This would be a Bad Thing(tm).
 */
void __i915_add_request(struct drm_i915_gem_request *request,
                        struct drm_i915_gem_object *obj,
                        bool flush_caches)
{
        struct intel_engine_cs *engine;
        struct drm_i915_private *dev_priv;
        struct intel_ringbuffer *ringbuf;
        u32 request_start;
        int ret;

        if (WARN_ON(request == NULL))
                return;

        engine = request->engine;
        dev_priv = request->i915;
        ringbuf = request->ringbuf;

        /*
         * To ensure that this call will not fail, space for its emissions
         * should already have been reserved in the ring buffer. Let the ring
         * know that it is time to use that space up.
         */
        intel_ring_reserved_space_use(ringbuf);

        request_start = intel_ring_get_tail(ringbuf);
        /*
         * Emit any outstanding flushes - execbuf can fail to emit the flush
         * after having emitted the batchbuffer command. Hence we need to fix
         * things up similar to emitting the lazy request. The difference here
         * is that the flush _must_ happen before the next request, no matter
         * what.
         */
        if (flush_caches) {
                if (i915.enable_execlists)
                        ret = logical_ring_flush_all_caches(request);
                else
                        ret = intel_ring_flush_all_caches(request);
                /* Not allowed to fail! */
                WARN(ret, "*_ring_flush_all_caches failed: %d!\n", ret);
        }

        trace_i915_gem_request_add(request);

        request->head = request_start;

        /* Whilst this request exists, batch_obj will be on the
         * active_list, and so will hold the active reference. Only when this
         * request is retired will the the batch_obj be moved onto the
         * inactive_list and lose its active reference. Hence we do not need
         * to explicitly hold another reference here.
         */
        request->batch_obj = obj;

        /* Seal the request and mark it as pending execution. Note that
         * we may inspect this state, without holding any locks, during
         * hangcheck. Hence we apply the barrier to ensure that we do not
         * see a more recent value in the hws than we are tracking.
         */
        request->emitted_jiffies = jiffies;
        request->previous_seqno = engine->last_submitted_seqno;
        smp_store_mb(engine->last_submitted_seqno, request->seqno);
        list_add_tail(&request->list, &engine->request_list);

        /* Record the position of the start of the request so that
         * should we detect the updated seqno part-way through the
         * GPU processing the request, we never over-estimate the
         * position of the head.
         */
        request->postfix = intel_ring_get_tail(ringbuf);

        if (i915.enable_execlists)
                ret = engine->emit_request(request);
        else {
                ret = engine->add_request(request);

                request->tail = intel_ring_get_tail(ringbuf);
        }
        /* Not allowed to fail! */
        WARN(ret, "emit|add_request failed: %d!\n", ret);

        i915_queue_hangcheck(engine->dev);

        queue_delayed_work(dev_priv->wq,
                           &dev_priv->mm.retire_work,
                           round_jiffies_up_relative(HZ));
        intel_mark_busy(dev_priv->dev);

        /* Sanity check that the reserved size was large enough. */
        intel_ring_reserved_space_end(ringbuf);
}

static bool i915_context_is_banned(struct drm_i915_private *dev_priv,
                                   const struct intel_context *ctx)
{
        unsigned long elapsed;

        elapsed = get_seconds() - ctx->hang_stats.guilty_ts;

        if (ctx->hang_stats.banned)
                return true;

        if (ctx->hang_stats.ban_period_seconds &&
            elapsed <= ctx->hang_stats.ban_period_seconds) {
                if (!i915_gem_context_is_default(ctx)) {
                        DRM_DEBUG("context hanging too fast, banning!\n");
                        return true;
                } else if (i915_stop_ring_allow_ban(dev_priv)) {
                        if (i915_stop_ring_allow_warn(dev_priv))
                                DRM_ERROR("gpu hanging too fast, banning!\n");
                        return true;
                }
        }

        return false;
}

static void i915_set_reset_status(struct drm_i915_private *dev_priv,
                                  struct intel_context *ctx,
                                  const bool guilty)
{
        struct i915_ctx_hang_stats *hs;

        if (WARN_ON(!ctx))
                return;

        hs = &ctx->hang_stats;

        if (guilty) {
                hs->banned = i915_context_is_banned(dev_priv, ctx);
                hs->batch_active++;
                hs->guilty_ts = get_seconds();
        } else {
                hs->batch_pending++;
        }
}

void i915_gem_request_free(struct kref *req_ref)
{
        struct drm_i915_gem_request *req = container_of(req_ref,
                                                 typeof(*req), ref);
        struct intel_context *ctx = req->ctx;

        if (req->file_priv)
                i915_gem_request_remove_from_client(req);

        if (ctx) {
                if (i915.enable_execlists && ctx != req->i915->kernel_context)
                        intel_lr_context_unpin(ctx, req->engine);

                i915_gem_context_unreference(ctx);
        }

        kmem_cache_free(req->i915->requests, req);
}

static inline int
__i915_gem_request_alloc(struct intel_engine_cs *engine,
                         struct intel_context *ctx,
                         struct drm_i915_gem_request **req_out)
{
        struct drm_i915_private *dev_priv = to_i915(engine->dev);
        unsigned reset_counter = i915_reset_counter(&dev_priv->gpu_error);
        struct drm_i915_gem_request *req;
        int ret;

        if (!req_out)
                return -EINVAL;

        *req_out = NULL;

        /* ABI: Before userspace accesses the GPU (e.g. execbuffer), report
         * EIO if the GPU is already wedged, or EAGAIN to drop the struct_mutex
         * and restart.
         */
        ret = i915_gem_check_wedge(reset_counter, dev_priv->mm.interruptible);
        if (ret)
                return ret;

        req = kmem_cache_zalloc(dev_priv->requests, GFP_KERNEL);
        if (req == NULL)
                return -ENOMEM;

        ret = i915_gem_get_seqno(engine->dev, &req->seqno);
        if (ret)
                goto err;

        kref_init(&req->ref);
        req->i915 = dev_priv;
        req->engine = engine;
        req->reset_counter = reset_counter;
        req->ctx  = ctx;
        i915_gem_context_reference(req->ctx);

        if (i915.enable_execlists)
                ret = intel_logical_ring_alloc_request_extras(req);
        else
                ret = intel_ring_alloc_request_extras(req);
        if (ret) {
                i915_gem_context_unreference(req->ctx);
                goto err;
        }

        /*
         * Reserve space in the ring buffer for all the commands required to
         * eventually emit this request. This is to guarantee that the
         * i915_add_request() call can't fail. Note that the reserve may need
         * to be redone if the request is not actually submitted straight
         * away, e.g. because a GPU scheduler has deferred it.
         */
        if (i915.enable_execlists)
                ret = intel_logical_ring_reserve_space(req);
        else
                ret = intel_ring_reserve_space(req);
        if (ret) {
                /*
                 * At this point, the request is fully allocated even if not
                 * fully prepared. Thus it can be cleaned up using the proper
                 * free code.
                 */
                intel_ring_reserved_space_cancel(req->ringbuf);
                i915_gem_request_unreference(req);
                return ret;
        }

        *req_out = req;
        return 0;

err:
        kmem_cache_free(dev_priv->requests, req);
        return ret;
}

/**
 * i915_gem_request_alloc - allocate a request structure
 *
 * @engine: engine that we wish to issue the request on.
 * @ctx: context that the request will be associated with.
 *       This can be NULL if the request is not directly related to
 *       any specific user context, in which case this function will
 *       choose an appropriate context to use.
 *
 * Returns a pointer to the allocated request if successful,
 * or an error code if not.
 */
struct drm_i915_gem_request *
i915_gem_request_alloc(struct intel_engine_cs *engine,
                       struct intel_context *ctx)
{
        struct drm_i915_gem_request *req;
        int err;

        if (ctx == NULL)
                ctx = to_i915(engine->dev)->kernel_context;
        err = __i915_gem_request_alloc(engine, ctx, &req);
        return err ? ERR_PTR(err) : req;
}

struct drm_i915_gem_request *
i915_gem_find_active_request(struct intel_engine_cs *engine)
{
        struct drm_i915_gem_request *request;

        list_for_each_entry(request, &engine->request_list, list) {
                if (i915_gem_request_completed(request, false))
                        continue;

                return request;
        }

        return NULL;
}

static void i915_gem_reset_engine_status(struct drm_i915_private *dev_priv,
                                       struct intel_engine_cs *engine)
{
        struct drm_i915_gem_request *request;
        bool ring_hung;

        request = i915_gem_find_active_request(engine);

        if (request == NULL)
                return;

        ring_hung = engine->hangcheck.score >= HANGCHECK_SCORE_RING_HUNG;

        i915_set_reset_status(dev_priv, request->ctx, ring_hung);

        list_for_each_entry_continue(request, &engine->request_list, list)
                i915_set_reset_status(dev_priv, request->ctx, false);
}

static void i915_gem_reset_engine_cleanup(struct drm_i915_private *dev_priv,
                                        struct intel_engine_cs *engine)
{
        struct intel_ringbuffer *buffer;

        while (!list_empty(&engine->active_list)) {
                struct drm_i915_gem_object *obj;

                obj = list_first_entry(&engine->active_list,
                                       struct drm_i915_gem_object,
                                       engine_list[engine->id]);

                i915_gem_object_retire__read(obj, engine->id);
        }

        /*
         * Clear the execlists queue up before freeing the requests, as those
         * are the ones that keep the context and ringbuffer backing objects
         * pinned in place.
         */

        if (i915.enable_execlists) {
                /* Ensure irq handler finishes or is cancelled. */
                tasklet_kill(&engine->irq_tasklet);

                spin_lock_bh(&engine->execlist_lock);
                /* list_splice_tail_init checks for empty lists */
                list_splice_tail_init(&engine->execlist_queue,
                                      &engine->execlist_retired_req_list);
                spin_unlock_bh(&engine->execlist_lock);

                intel_execlists_retire_requests(engine);
        }

        /*
         * We must free the requests after all the corresponding objects have
         * been moved off active lists. Which is the same order as the normal
         * retire_requests function does. This is important if object hold
         * implicit references on things like e.g. ppgtt address spaces through
         * the request.
         */
        while (!list_empty(&engine->request_list)) {
                struct drm_i915_gem_request *request;

                request = list_first_entry(&engine->request_list,
                                           struct drm_i915_gem_request,
                                           list);

                i915_gem_request_retire(request);
        }

        /* Having flushed all requests from all queues, we know that all
         * ringbuffers must now be empty. However, since we do not reclaim
         * all space when retiring the request (to prevent HEADs colliding
         * with rapid ringbuffer wraparound) the amount of available space
         * upon reset is less than when we start. Do one more pass over
         * all the ringbuffers to reset last_retired_head.
         */
        list_for_each_entry(buffer, &engine->buffers, link) {
                buffer->last_retired_head = buffer->tail;
                intel_ring_update_space(buffer);
        }

        intel_ring_init_seqno(engine, engine->last_submitted_seqno);
}

void i915_gem_reset(struct drm_device *dev)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct intel_engine_cs *engine;

        /*
         * Before we free the objects from the requests, we need to inspect
         * them for finding the guilty party. As the requests only borrow
         * their reference to the objects, the inspection must be done first.
         */
        for_each_engine(engine, dev_priv)
                i915_gem_reset_engine_status(dev_priv, engine);

        for_each_engine(engine, dev_priv)
                i915_gem_reset_engine_cleanup(dev_priv, engine);

        i915_gem_context_reset(dev);

        i915_gem_restore_fences(dev);

        WARN_ON(i915_verify_lists(dev));
}

/**
 * This function clears the request list as sequence numbers are passed.
 */
void
i915_gem_retire_requests_ring(struct intel_engine_cs *engine)
{
        WARN_ON(i915_verify_lists(engine->dev));

        /* Retire requests first as we use it above for the early return.
         * If we retire requests last, we may use a later seqno and so clear
         * the requests lists without clearing the active list, leading to
         * confusion.
         */
        while (!list_empty(&engine->request_list)) {
                struct drm_i915_gem_request *request;

                request = list_first_entry(&engine->request_list,
                                           struct drm_i915_gem_request,
                                           list);

                if (!i915_gem_request_completed(request, true))
                        break;

                i915_gem_request_retire(request);
        }

        /* Move any buffers on the active list that are no longer referenced
         * by the ringbuffer to the flushing/inactive lists as appropriate,
         * before we free the context associated with the requests.
         */
        while (!list_empty(&engine->active_list)) {
                struct drm_i915_gem_object *obj;

                obj = list_first_entry(&engine->active_list,
                                       struct drm_i915_gem_object,
                                       engine_list[engine->id]);

                if (!list_empty(&obj->last_read_req[engine->id]->list))
                        break;

                i915_gem_object_retire__read(obj, engine->id);
        }

        if (unlikely(engine->trace_irq_req &&
                     i915_gem_request_completed(engine->trace_irq_req, true))) {
                engine->irq_put(engine);

                i915_gem_request_assign(&engine->trace_irq_req, NULL);
        }

        WARN_ON(i915_verify_lists(engine->dev));
}

bool
i915_gem_retire_requests(struct drm_device *dev)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct intel_engine_cs *engine;
        bool idle = true;

        for_each_engine(engine, dev_priv) {
                i915_gem_retire_requests_ring(engine);
                idle &= list_empty(&engine->request_list);
                if (i915.enable_execlists) {
                        spin_lock_bh(&engine->execlist_lock);
                        idle &= list_empty(&engine->execlist_queue);
                        spin_unlock_bh(&engine->execlist_lock);

                        intel_execlists_retire_requests(engine);
                }
        }

        if (idle)
                mod_delayed_work(dev_priv->wq,
                                   &dev_priv->mm.idle_work,
                                   msecs_to_jiffies(100));

        return idle;
}

static void
i915_gem_retire_work_handler(struct work_struct *work)
{
        struct drm_i915_private *dev_priv =
                container_of(work, typeof(*dev_priv), mm.retire_work.work);
        struct drm_device *dev = dev_priv->dev;
        bool idle;

        /* Come back later if the device is busy... */
        idle = false;
        if (mutex_trylock(&dev->struct_mutex)) {
                idle = i915_gem_retire_requests(dev);
                mutex_unlock(&dev->struct_mutex);
        }
        if (!idle)
                queue_delayed_work(dev_priv->wq, &dev_priv->mm.retire_work,
                                   round_jiffies_up_relative(HZ));
}

static void
i915_gem_idle_work_handler(struct work_struct *work)
{
        struct drm_i915_private *dev_priv =
                container_of(work, typeof(*dev_priv), mm.idle_work.work);
        struct drm_device *dev = dev_priv->dev;
        struct intel_engine_cs *engine;

        for_each_engine(engine, dev_priv)
                if (!list_empty(&engine->request_list))
                        return;

        /* we probably should sync with hangcheck here, using cancel_work_sync.
         * Also locking seems to be fubar here, engine->request_list is protected
         * by dev->struct_mutex. */

        intel_mark_idle(dev);

        if (mutex_trylock(&dev->struct_mutex)) {
                for_each_engine(engine, dev_priv)
                        i915_gem_batch_pool_fini(&engine->batch_pool);

                mutex_unlock(&dev->struct_mutex);
        }
}

/**
 * Ensures that an object will eventually get non-busy by flushing any required
 * write domains, emitting any outstanding lazy request and retiring and
 * completed requests.
 */
static int
i915_gem_object_flush_active(struct drm_i915_gem_object *obj)
{
        int i;

        if (!obj->active)
                return 0;

        for (i = 0; i < I915_NUM_ENGINES; i++) {
                struct drm_i915_gem_request *req;

                req = obj->last_read_req[i];
                if (req == NULL)
                        continue;

                if (list_empty(&req->list))
                        goto retire;

                if (i915_gem_request_completed(req, true)) {
                        __i915_gem_request_retire__upto(req);
retire:
                        i915_gem_object_retire__read(obj, i);
                }
        }

        return 0;
}

/**
 * i915_gem_wait_ioctl - implements DRM_IOCTL_I915_GEM_WAIT
 * @DRM_IOCTL_ARGS: standard ioctl arguments
 *
 * Returns 0 if successful, else an error is returned with the remaining time in
 * the timeout parameter.
 *  -ETIME: object is still busy after timeout
 *  -ERESTARTSYS: signal interrupted the wait
 *  -ENONENT: object doesn't exist
 * Also possible, but rare:
 *  -EAGAIN: GPU wedged
 *  -ENOMEM: damn
 *  -ENODEV: Internal IRQ fail
 *  -E?: The add request failed
 *
 * The wait ioctl with a timeout of 0 reimplements the busy ioctl. With any
 * non-zero timeout parameter the wait ioctl will wait for the given number of
 * nanoseconds on an object becoming unbusy. Since the wait itself does so
 * without holding struct_mutex the object may become re-busied before this
 * function completes. A similar but shorter * race condition exists in the busy
 * ioctl
 */
int
i915_gem_wait_ioctl(struct drm_device *dev, void *data, struct drm_file *file)
{
        struct drm_i915_gem_wait *args = data;
        struct drm_i915_gem_object *obj;
        struct drm_i915_gem_request *req[I915_NUM_ENGINES];
        int i, n = 0;
        int ret;

        if (args->flags != 0)
                return -EINVAL;

        ret = i915_mutex_lock_interruptible(dev);
        if (ret)
                return ret;

        obj = to_intel_bo(drm_gem_object_lookup(file, args->bo_handle));
        if (&obj->base == NULL) {
                mutex_unlock(&dev->struct_mutex);
                return -ENOENT;
        }

        /* Need to make sure the object gets inactive eventually. */
        ret = i915_gem_object_flush_active(obj);
        if (ret)
                goto out;

        if (!obj->active)
                goto out;

        /* Do this after OLR check to make sure we make forward progress polling
         * on this IOCTL with a timeout == 0 (like busy ioctl)
         */
        if (args->timeout_ns == 0) {
                ret = -ETIME;
                goto out;
        }

        drm_gem_object_unreference(&obj->base);

        for (i = 0; i < I915_NUM_ENGINES; i++) {
                if (obj->last_read_req[i] == NULL)
                        continue;

                req[n++] = i915_gem_request_reference(obj->last_read_req[i]);
        }

        mutex_unlock(&dev->struct_mutex);

        for (i = 0; i < n; i++) {
                if (ret == 0)
                        ret = __i915_wait_request(req[i], true,
                                                  args->timeout_ns > 0 ? &args->timeout_ns : NULL,
                                                  to_rps_client(file));
                i915_gem_request_unreference__unlocked(req[i]);
        }
        return ret;

out:
        drm_gem_object_unreference(&obj->base);
        mutex_unlock(&dev->struct_mutex);
        return ret;
}

static int
__i915_gem_object_sync(struct drm_i915_gem_object *obj,
                       struct intel_engine_cs *to,
                       struct drm_i915_gem_request *from_req,
                       struct drm_i915_gem_request **to_req)
{
        struct intel_engine_cs *from;
        int ret;

        from = i915_gem_request_get_engine(from_req);
        if (to == from)
                return 0;

        if (i915_gem_request_completed(from_req, true))
                return 0;

        if (!i915_semaphore_is_enabled(obj->base.dev)) {
                struct drm_i915_private *i915 = to_i915(obj->base.dev);
                ret = __i915_wait_request(from_req,
                                          i915->mm.interruptible,
                                          NULL,
                                          &i915->rps.semaphores);
                if (ret)
                        return ret;

                i915_gem_object_retire_request(obj, from_req);
        } else {
                int idx = intel_ring_sync_index(from, to);
                u32 seqno = i915_gem_request_get_seqno(from_req);

                WARN_ON(!to_req);

                if (seqno <= from->semaphore.sync_seqno[idx])
                        return 0;

                if (*to_req == NULL) {
                        struct drm_i915_gem_request *req;

                        req = i915_gem_request_alloc(to, NULL);
                        if (IS_ERR(req))
                                return PTR_ERR(req);

                        *to_req = req;
                }

                trace_i915_gem_ring_sync_to(*to_req, from, from_req);
                ret = to->semaphore.sync_to(*to_req, from, seqno);
                if (ret)
                        return ret;

                /* We use last_read_req because sync_to()
                 * might have just caused seqno wrap under
                 * the radar.
                 */
                from->semaphore.sync_seqno[idx] =
                        i915_gem_request_get_seqno(obj->last_read_req[from->id]);
        }

        return 0;
}

/**
 * i915_gem_object_sync - sync an object to a ring.
 *
 * @obj: object which may be in use on another ring.
 * @to: ring we wish to use the object on. May be NULL.
 * @to_req: request we wish to use the object for. See below.
 *          This will be allocated and returned if a request is
 *          required but not passed in.
 *
 * This code is meant to abstract object synchronization with the GPU.
 * Calling with NULL implies synchronizing the object with the CPU
 * rather than a particular GPU ring. Conceptually we serialise writes
 * between engines inside the GPU. We only allow one engine to write
 * into a buffer at any time, but multiple readers. To ensure each has
 * a coherent view of memory, we must:
 *
 * - If there is an outstanding write request to the object, the new
 *   request must wait for it to complete (either CPU or in hw, requests
 *   on the same ring will be naturally ordered).
 *
 * - If we are a write request (pending_write_domain is set), the new
 *   request must wait for outstanding read requests to complete.
 *
 * For CPU synchronisation (NULL to) no request is required. For syncing with
 * rings to_req must be non-NULL. However, a request does not have to be
 * pre-allocated. If *to_req is NULL and sync commands will be emitted then a
 * request will be allocated automatically and returned through *to_req. Note
 * that it is not guaranteed that commands will be emitted (because the system
 * might already be idle). Hence there is no need to create a request that
 * might never have any work submitted. Note further that if a request is
 * returned in *to_req, it is the responsibility of the caller to submit
 * that request (after potentially adding more work to it).
 *
 * Returns 0 if successful, else propagates up the lower layer error.
 */
int
i915_gem_object_sync(struct drm_i915_gem_object *obj,
                     struct intel_engine_cs *to,
                     struct drm_i915_gem_request **to_req)
{
        const bool readonly = obj->base.pending_write_domain == 0;
        struct drm_i915_gem_request *req[I915_NUM_ENGINES];
        int ret, i, n;

        if (!obj->active)
                return 0;

        if (to == NULL)
                return i915_gem_object_wait_rendering(obj, readonly);

        n = 0;
        if (readonly) {
                if (obj->last_write_req)
                        req[n++] = obj->last_write_req;
        } else {
                for (i = 0; i < I915_NUM_ENGINES; i++)
                        if (obj->last_read_req[i])
                                req[n++] = obj->last_read_req[i];
        }
        for (i = 0; i < n; i++) {
                ret = __i915_gem_object_sync(obj, to, req[i], to_req);
                if (ret)
                        return ret;
        }

        return 0;
}

static void i915_gem_object_finish_gtt(struct drm_i915_gem_object *obj)
{
        u32 old_write_domain, old_read_domains;

        /* Force a pagefault for domain tracking on next user access */
        i915_gem_release_mmap(obj);

        if ((obj->base.read_domains & I915_GEM_DOMAIN_GTT) == 0)
                return;

        old_read_domains = obj->base.read_domains;
        old_write_domain = obj->base.write_domain;

        obj->base.read_domains &= ~I915_GEM_DOMAIN_GTT;
        obj->base.write_domain &= ~I915_GEM_DOMAIN_GTT;

        trace_i915_gem_object_change_domain(obj,
                                            old_read_domains,
                                            old_write_domain);
}

static int __i915_vma_unbind(struct i915_vma *vma, bool wait)
{
        struct drm_i915_gem_object *obj = vma->obj;
        struct drm_i915_private *dev_priv = obj->base.dev->dev_private;
        int ret;

        if (list_empty(&vma->obj_link))
                return 0;

        if (!drm_mm_node_allocated(&vma->node)) {
                i915_gem_vma_destroy(vma);
                return 0;
        }

        if (vma->pin_count)
                return -EBUSY;

        BUG_ON(obj->pages == NULL);

        if (wait) {
                ret = i915_gem_object_wait_rendering(obj, false);
                if (ret)
                        return ret;
        }

        if (vma->is_ggtt && vma->ggtt_view.type == I915_GGTT_VIEW_NORMAL) {
                i915_gem_object_finish_gtt(obj);

                /* release the fence reg _after_ flushing */
                ret = i915_gem_object_put_fence(obj);
                if (ret)
                        return ret;
        }

        trace_i915_vma_unbind(vma);

        vma->vm->unbind_vma(vma);
        vma->bound = 0;

        list_del_init(&vma->vm_link);
        if (vma->is_ggtt) {
                if (vma->ggtt_view.type == I915_GGTT_VIEW_NORMAL) {
                        obj->map_and_fenceable = false;
                } else if (vma->ggtt_view.pages) {
                        sg_free_table(vma->ggtt_view.pages);
                        kfree(vma->ggtt_view.pages);
                }
                vma->ggtt_view.pages = NULL;
        }

        drm_mm_remove_node(&vma->node);
        i915_gem_vma_destroy(vma);

        /* Since the unbound list is global, only move to that list if
         * no more VMAs exist. */
        if (list_empty(&obj->vma_list))
                list_move_tail(&obj->global_list, &dev_priv->mm.unbound_list);

        /* And finally now the object is completely decoupled from this vma,
         * we can drop its hold on the backing storage and allow it to be
         * reaped by the shrinker.
         */
        i915_gem_object_unpin_pages(obj);

        return 0;
}

int i915_vma_unbind(struct i915_vma *vma)
{
        return __i915_vma_unbind(vma, true);
}

int __i915_vma_unbind_no_wait(struct i915_vma *vma)
{
        return __i915_vma_unbind(vma, false);
}

int i915_gpu_idle(struct drm_device *dev)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct intel_engine_cs *engine;
        int ret;

        /* Flush everything onto the inactive list. */
        for_each_engine(engine, dev_priv) {
                if (!i915.enable_execlists) {
                        struct drm_i915_gem_request *req;

                        req = i915_gem_request_alloc(engine, NULL);
                        if (IS_ERR(req))
                                return PTR_ERR(req);

                        ret = i915_switch_context(req);
                        i915_add_request_no_flush(req);
                        if (ret)
                                return ret;
                }

                ret = intel_engine_idle(engine);
                if (ret)
                        return ret;
        }

        WARN_ON(i915_verify_lists(dev));
        return 0;
}

static bool i915_gem_valid_gtt_space(struct i915_vma *vma,
                                     unsigned long cache_level)
{
        struct drm_mm_node *gtt_space = &vma->node;
        struct drm_mm_node *other;

        /*
         * On some machines we have to be careful when putting differing types
         * of snoopable memory together to avoid the prefetcher crossing memory
         * domains and dying. During vm initialisation, we decide whether or not
         * these constraints apply and set the drm_mm.color_adjust
         * appropriately.
         */
        if (vma->vm->mm.color_adjust == NULL)
                return true;

        if (!drm_mm_node_allocated(gtt_space))
                return true;

        if (list_empty(&gtt_space->node_list))
                return true;

        other = list_entry(gtt_space->node_list.prev, struct drm_mm_node, node_list);
        if (other->allocated && !other->hole_follows && other->color != cache_level)
                return false;

        other = list_entry(gtt_space->node_list.next, struct drm_mm_node, node_list);
        if (other->allocated && !gtt_space->hole_follows && other->color != cache_level)
                return false;

        return true;
}

/**
 * Finds free space in the GTT aperture and binds the object or a view of it
 * there.
 */
static struct i915_vma *
i915_gem_object_bind_to_vm(struct drm_i915_gem_object *obj,
                           struct i915_address_space *vm,
                           const struct i915_ggtt_view *ggtt_view,
                           unsigned alignment,
                           uint64_t flags)
{
        struct drm_device *dev = obj->base.dev;
        struct drm_i915_private *dev_priv = to_i915(dev);
        struct i915_ggtt *ggtt = &dev_priv->ggtt;
        u32 fence_alignment, unfenced_alignment;
        u32 search_flag, alloc_flag;
        u64 start, end;
        u64 size, fence_size;
        struct i915_vma *vma;
        int ret;

        if (i915_is_ggtt(vm)) {
                u32 view_size;

                if (WARN_ON(!ggtt_view))
                        return ERR_PTR(-EINVAL);

                view_size = i915_ggtt_view_size(obj, ggtt_view);

                fence_size = i915_gem_get_gtt_size(dev,
                                                   view_size,
                                                   obj->tiling_mode);
                fence_alignment = i915_gem_get_gtt_alignment(dev,
                                                             view_size,
                                                             obj->tiling_mode,
                                                             true);
                unfenced_alignment = i915_gem_get_gtt_alignment(dev,
                                                                view_size,
                                                                obj->tiling_mode,
                                                                false);
                size = flags & PIN_MAPPABLE ? fence_size : view_size;
        } else {
                fence_size = i915_gem_get_gtt_size(dev,
                                                   obj->base.size,
                                                   obj->tiling_mode);
                fence_alignment = i915_gem_get_gtt_alignment(dev,
                                                             obj->base.size,
                                                             obj->tiling_mode,
                                                             true);
                unfenced_alignment =
                        i915_gem_get_gtt_alignment(dev,
                                                   obj->base.size,
                                                   obj->tiling_mode,
                                                   false);
                size = flags & PIN_MAPPABLE ? fence_size : obj->base.size;
        }

        start = flags & PIN_OFFSET_BIAS ? flags & PIN_OFFSET_MASK : 0;
        end = vm->total;
        if (flags & PIN_MAPPABLE)
                end = min_t(u64, end, ggtt->mappable_end);
        if (flags & PIN_ZONE_4G)
                end = min_t(u64, end, (1ULL << 32) - PAGE_SIZE);

        if (alignment == 0)
                alignment = flags & PIN_MAPPABLE ? fence_alignment :
                                                unfenced_alignment;
        if (flags & PIN_MAPPABLE && alignment & (fence_alignment - 1)) {
                DRM_DEBUG("Invalid object (view type=%u) alignment requested %u\n",
                          ggtt_view ? ggtt_view->type : 0,
                          alignment);
                return ERR_PTR(-EINVAL);
        }

        /* If binding the object/GGTT view requires more space than the entire
         * aperture has, reject it early before evicting everything in a vain
         * attempt to find space.
         */
        if (size > end) {
                DRM_DEBUG("Attempting to bind an object (view type=%u) larger than the aperture: size=%llu > %s aperture=%llu\n",
                          ggtt_view ? ggtt_view->type : 0,
                          size,
                          flags & PIN_MAPPABLE ? "mappable" : "total",
                          end);
                return ERR_PTR(-E2BIG);
        }

        ret = i915_gem_object_get_pages(obj);
        if (ret)
                return ERR_PTR(ret);

        i915_gem_object_pin_pages(obj);

        vma = ggtt_view ? i915_gem_obj_lookup_or_create_ggtt_vma(obj, ggtt_view) :
                          i915_gem_obj_lookup_or_create_vma(obj, vm);

        if (IS_ERR(vma))
                goto err_unpin;

        if (flags & PIN_OFFSET_FIXED) {
                uint64_t offset = flags & PIN_OFFSET_MASK;

                if (offset & (alignment - 1) || offset + size > end) {
                        ret = -EINVAL;
                        goto err_free_vma;
                }
                vma->node.start = offset;
                vma->node.size = size;
                vma->node.color = obj->cache_level;
                ret = drm_mm_reserve_node(&vm->mm, &vma->node);
                if (ret) {
                        ret = i915_gem_evict_for_vma(vma);
                        if (ret == 0)
                                ret = drm_mm_reserve_node(&vm->mm, &vma->node);
                }
                if (ret)
                        goto err_free_vma;
        } else {
                if (flags & PIN_HIGH) {
                        search_flag = DRM_MM_SEARCH_BELOW;
                        alloc_flag = DRM_MM_CREATE_TOP;
                } else {
                        search_flag = DRM_MM_SEARCH_DEFAULT;
                        alloc_flag = DRM_MM_CREATE_DEFAULT;
                }

search_free:
                ret = drm_mm_insert_node_in_range_generic(&vm->mm, &vma->node,
                                                          size, alignment,
                                                          obj->cache_level,
                                                          start, end,
                                                          search_flag,
                                                          alloc_flag);
                if (ret) {
                        ret = i915_gem_evict_something(dev, vm, size, alignment,
                                                       obj->cache_level,
                                                       start, end,
                                                       flags);
                        if (ret == 0)
                                goto search_free;

                        goto err_free_vma;
                }
        }
        if (WARN_ON(!i915_gem_valid_gtt_space(vma, obj->cache_level))) {
                ret = -EINVAL;
                goto err_remove_node;
        }

        trace_i915_vma_bind(vma, flags);
        ret = i915_vma_bind(vma, obj->cache_level, flags);
        if (ret)
                goto err_remove_node;

        list_move_tail(&obj->global_list, &dev_priv->mm.bound_list);
        list_add_tail(&vma->vm_link, &vm->inactive_list);

        return vma;

err_remove_node:
        drm_mm_remove_node(&vma->node);
err_free_vma:
        i915_gem_vma_destroy(vma);
        vma = ERR_PTR(ret);
err_unpin:
        i915_gem_object_unpin_pages(obj);
        return vma;
}

bool
i915_gem_clflush_object(struct drm_i915_gem_object *obj,
                        bool force)
{
        /* If we don't have a page list set up, then we're not pinned
         * to GPU, and we can ignore the cache flush because it'll happen
         * again at bind time.
         */
        if (obj->pages == NULL)
                return false;

        /*
         * Stolen memory is always coherent with the GPU as it is explicitly
         * marked as wc by the system, or the system is cache-coherent.
         */
        if (obj->stolen || obj->phys_handle)
                return false;

        /* If the GPU is snooping the contents of the CPU cache,
         * we do not need to manually clear the CPU cache lines.  However,
         * the caches are only snooped when the render cache is
         * flushed/invalidated.  As we always have to emit invalidations
         * and flushes when moving into and out of the RENDER domain, correct
         * snooping behaviour occurs naturally as the result of our domain
         * tracking.
         */
        if (!force && cpu_cache_is_coherent(obj->base.dev, obj->cache_level)) {
                obj->cache_dirty = true;
                return false;
        }

        trace_i915_gem_object_clflush(obj);
        drm_clflush_sg(obj->pages);
        obj->cache_dirty = false;

        return true;
}

/** Flushes the GTT write domain for the object if it's dirty. */
static void
i915_gem_object_flush_gtt_write_domain(struct drm_i915_gem_object *obj)
{
        uint32_t old_write_domain;

        if (obj->base.write_domain != I915_GEM_DOMAIN_GTT)
                return;

        /* No actual flushing is required for the GTT write domain.  Writes
         * to it immediately go to main memory as far as we know, so there's
         * no chipset flush.  It also doesn't land in render cache.
         *
         * However, we do have to enforce the order so that all writes through
         * the GTT land before any writes to the device, such as updates to
         * the GATT itself.
         */
        wmb();

        old_write_domain = obj->base.write_domain;
        obj->base.write_domain = 0;

        intel_fb_obj_flush(obj, false, ORIGIN_GTT);

        trace_i915_gem_object_change_domain(obj,
                                            obj->base.read_domains,
                                            old_write_domain);
}

/** Flushes the CPU write domain for the object if it's dirty. */
static void
i915_gem_object_flush_cpu_write_domain(struct drm_i915_gem_object *obj)
{
        uint32_t old_write_domain;

        if (obj->base.write_domain != I915_GEM_DOMAIN_CPU)
                return;

        if (i915_gem_clflush_object(obj, obj->pin_display))
                i915_gem_chipset_flush(obj->base.dev);

        old_write_domain = obj->base.write_domain;
        obj->base.write_domain = 0;

        intel_fb_obj_flush(obj, false, ORIGIN_CPU);

        trace_i915_gem_object_change_domain(obj,
                                            obj->base.read_domains,
                                            old_write_domain);
}

/**
 * Moves a single object to the GTT read, and possibly write domain.
 *
 * This function returns when the move is complete, including waiting on
 * flushes to occur.
 */
int
i915_gem_object_set_to_gtt_domain(struct drm_i915_gem_object *obj, bool write)
{
        struct drm_device *dev = obj->base.dev;
        struct drm_i915_private *dev_priv = to_i915(dev);
        struct i915_ggtt *ggtt = &dev_priv->ggtt;
        uint32_t old_write_domain, old_read_domains;
        struct i915_vma *vma;
        int ret;

        if (obj->base.write_domain == I915_GEM_DOMAIN_GTT)
                return 0;

        ret = i915_gem_object_wait_rendering(obj, !write);
        if (ret)
                return ret;

        /* Flush and acquire obj->pages so that we are coherent through
         * direct access in memory with previous cached writes through
         * shmemfs and that our cache domain tracking remains valid.
         * For example, if the obj->filp was moved to swap without us
         * being notified and releasing the pages, we would mistakenly
         * continue to assume that the obj remained out of the CPU cached
         * domain.
         */
        ret = i915_gem_object_get_pages(obj);
        if (ret)
                return ret;

        i915_gem_object_flush_cpu_write_domain(obj);

        /* Serialise direct access to this object with the barriers for
         * coherent writes from the GPU, by effectively invalidating the
         * GTT domain upon first access.
         */
        if ((obj->base.read_domains & I915_GEM_DOMAIN_GTT) == 0)
                mb();

        old_write_domain = obj->base.write_domain;
        old_read_domains = obj->base.read_domains;

        /* It should now be out of any other write domains, and we can update
         * the domain values for our changes.
         */
        BUG_ON((obj->base.write_domain & ~I915_GEM_DOMAIN_GTT) != 0);
        obj->base.read_domains |= I915_GEM_DOMAIN_GTT;
        if (write) {
                obj->base.read_domains = I915_GEM_DOMAIN_GTT;
                obj->base.write_domain = I915_GEM_DOMAIN_GTT;
                obj->dirty = 1;
        }

        trace_i915_gem_object_change_domain(obj,
                                            old_read_domains,
                                            old_write_domain);

        /* And bump the LRU for this access */
        vma = i915_gem_obj_to_ggtt(obj);
        if (vma && drm_mm_node_allocated(&vma->node) && !obj->active)
                list_move_tail(&vma->vm_link,
                               &ggtt->base.inactive_list);

        return 0;
}

/**
 * Changes the cache-level of an object across all VMA.
 *
 * After this function returns, the object will be in the new cache-level
 * across all GTT and the contents of the backing storage will be coherent,
 * with respect to the new cache-level. In order to keep the backing storage
 * coherent for all users, we only allow a single cache level to be set
 * globally on the object and prevent it from being changed whilst the
 * hardware is reading from the object. That is if the object is currently
 * on the scanout it will be set to uncached (or equivalent display
 * cache coherency) and all non-MOCS GPU access will also be uncached so
 * that all direct access to the scanout remains coherent.
 */
int i915_gem_object_set_cache_level(struct drm_i915_gem_object *obj,
                                    enum i915_cache_level cache_level)
{
        struct drm_device *dev = obj->base.dev;
        struct i915_vma *vma, *next;
        bool bound = false;
        int ret = 0;

        if (obj->cache_level == cache_level)
                goto out;

        /* Inspect the list of currently bound VMA and unbind any that would
         * be invalid given the new cache-level. This is principally to
         * catch the issue of the CS prefetch crossing page boundaries and
         * reading an invalid PTE on older architectures.
         */
        list_for_each_entry_safe(vma, next, &obj->vma_list, obj_link) {
                if (!drm_mm_node_allocated(&vma->node))
                        continue;

                if (vma->pin_count) {
                        DRM_DEBUG("can not change the cache level of pinned objects\n");
                        return -EBUSY;
                }

                if (!i915_gem_valid_gtt_space(vma, cache_level)) {
                        ret = i915_vma_unbind(vma);
                        if (ret)
                                return ret;
                } else
                        bound = true;
        }

        /* We can reuse the existing drm_mm nodes but need to change the
         * cache-level on the PTE. We could simply unbind them all and
         * rebind with the correct cache-level on next use. However since
         * we already have a valid slot, dma mapping, pages etc, we may as
         * rewrite the PTE in the belief that doing so tramples upon less
         * state and so involves less work.
         */
        if (bound) {
                /* Before we change the PTE, the GPU must not be accessing it.
                 * If we wait upon the object, we know that all the bound
                 * VMA are no longer active.
                 */
                ret = i915_gem_object_wait_rendering(obj, false);
                if (ret)
                        return ret;

                if (!HAS_LLC(dev) && cache_level != I915_CACHE_NONE) {
                        /* Access to snoopable pages through the GTT is
                         * incoherent and on some machines causes a hard
                         * lockup. Relinquish the CPU mmaping to force
                         * userspace to refault in the pages and we can
                         * then double check if the GTT mapping is still
                         * valid for that pointer access.
                         */
                        i915_gem_release_mmap(obj);

                        /* As we no longer need a fence for GTT access,
                         * we can relinquish it now (and so prevent having
                         * to steal a fence from someone else on the next
                         * fence request). Note GPU activity would have
                         * dropped the fence as all snoopable access is
                         * supposed to be linear.
                         */
                        ret = i915_gem_object_put_fence(obj);
                        if (ret)
                                return ret;
                } else {
                        /* We either have incoherent backing store and
                         * so no GTT access or the architecture is fully
                         * coherent. In such cases, existing GTT mmaps
                         * ignore the cache bit in the PTE and we can
                         * rewrite it without confusing the GPU or having
                         * to force userspace to fault back in its mmaps.
                         */
                }

                list_for_each_entry(vma, &obj->vma_list, obj_link) {
                        if (!drm_mm_node_allocated(&vma->node))
                                continue;

                        ret = i915_vma_bind(vma, cache_level, PIN_UPDATE);
                        if (ret)
                                return ret;
                }
        }

        list_for_each_entry(vma, &obj->vma_list, obj_link)
                vma->node.color = cache_level;
        obj->cache_level = cache_level;

out:
        /* Flush the dirty CPU caches to the backing storage so that the
         * object is now coherent at its new cache level (with respect
         * to the access domain).
         */
        if (obj->cache_dirty &&
            obj->base.write_domain != I915_GEM_DOMAIN_CPU &&
            cpu_write_needs_clflush(obj)) {
                if (i915_gem_clflush_object(obj, true))
                        i915_gem_chipset_flush(obj->base.dev);
        }

        return 0;
}

int i915_gem_get_caching_ioctl(struct drm_device *dev, void *data,
                               struct drm_file *file)
{
        struct drm_i915_gem_caching *args = data;
        struct drm_i915_gem_object *obj;

        obj = to_intel_bo(drm_gem_object_lookup(file, args->handle));
        if (&obj->base == NULL)
                return -ENOENT;

        switch (obj->cache_level) {
        case I915_CACHE_LLC:
        case I915_CACHE_L3_LLC:
                args->caching = I915_CACHING_CACHED;
                break;

        case I915_CACHE_WT:
                args->caching = I915_CACHING_DISPLAY;
                break;

        default:
                args->caching = I915_CACHING_NONE;
                break;
        }

        drm_gem_object_unreference_unlocked(&obj->base);
        return 0;
}

int i915_gem_set_caching_ioctl(struct drm_device *dev, void *data,
                               struct drm_file *file)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct drm_i915_gem_caching *args = data;
        struct drm_i915_gem_object *obj;
        enum i915_cache_level level;
        int ret;

        switch (args->caching) {
        case I915_CACHING_NONE:
                level = I915_CACHE_NONE;
                break;
        case I915_CACHING_CACHED:
                /*
                 * Due to a HW issue on BXT A stepping, GPU stores via a
                 * snooped mapping may leave stale data in a corresponding CPU
                 * cacheline, whereas normally such cachelines would get
                 * invalidated.
                 */
                if (!HAS_LLC(dev) && !HAS_SNOOP(dev))
                        return -ENODEV;

                level = I915_CACHE_LLC;
                break;
        case I915_CACHING_DISPLAY:
                level = HAS_WT(dev) ? I915_CACHE_WT : I915_CACHE_NONE;
                break;
        default:
                return -EINVAL;
        }

        intel_runtime_pm_get(dev_priv);